Feature dotnet wrapper

[mortensp]

1. DDS_Core added as a wrapper for .Net applications.
2. DDS_Core_Demo contains examples using most of the methods in dll.lib via the new wrapper.
3. In dds I have added dds_api.h with 'EXTERN_C DLLEXPORT' on the the SolverComtext methods.
4. In the docs is a new dotnet_interface.md file deskribing the new wrapper and a link is made in the ReadMe.md file.
5. The build warning on Directory.Build.props has been totally eliminated.
6. I'm considering a Nuget package for the wrapper, but for that to work on MacOs i'll need a MacOs version of dds_native from someone:-)

Note: I have not been able to build using Bazel, so everything has been done i VS.

[Copilot]

Pull request overview

This PR introduces a new .NET wrapper layer (DDS_Core) over the DDS native engine, adds a demo application, and wires up Visual Studio projects to produce a dds_native DLL intended for P/Invoke consumption. It also updates the public C++ headers to expose additional context-aware entry points and adds documentation for the new .NET interface.

Changes:

• Add a new native DLL project (dds_native) and a new C-export wrapper header intended for .NET P/Invoke.
• Add DDS_Core (.NET 8) plus DDS_Core_Demo with typed interop models and example usage.
• Update solution/VS project output paths and add docs/README links for the .NET interface.

Reviewed changes

Copilot reviewed 94 out of 95 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
solution/solve_board.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/solve_board_pbn.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/solve_all_boards.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/Solution.slnx	Adds dds_native project and build dependencies.
solution/par.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/migration_example.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/hands.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/dealer_par.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/DDS.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/dds_native.vcxproj.filters	Adds VS filter mapping for native DLL project sources/headers.
solution/dds_native.vcxproj	Adds native DLL project that compiles DDS sources into dds_native.
solution/calc_par_context_example.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/calc_dd_table.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/calc_all_tables.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/calc_all_tables_pbn.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/analyse_play_pbn.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/analyse_play_bin.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
solution/analyse_all_plays_bin.vcxproj	Removes explicit props import; updates OutDir/IntDir paths.
README.md	Adds link to the new .NET interface documentation.
library/src/solver_context/solver_context.cpp	Minor comment change near includes/ctor initializer list.
library/src/api/dds_api.hpp	Adds new C-export wrapper surface intended for .NET interop.
library/src/api/calc_par.hpp	Updates context-aware calc_par declaration with export/linkage macros.
library/src/api/calc_dd_table.hpp	Updates context-aware calc_dd_table* declarations with export/linkage macros.
library/src/api/BUILD.bazel	Adds dds_api.hpp to the API Bazel target headers.
dotnet/Directory.Build.props	Adds shared MSBuild properties for .NET projects (output paths, warnings, etc.).
dotnet/DDS_Core/Properties/launchSettings.json	Enables mixed managed/native debugging for DDS_Core.
dotnet/DDS_Core/Native/DdsNative.cs	Declares P/Invoke signatures for legacy and new context-based entry points.
dotnet/DDS_Core/Helpers/stringArray2xDebugView.cs	Debugger proxy helper for 2-row string buffers.
dotnet/DDS_Core/Helpers/stringArray2x16.cs	Fixed-size 2x16 ASCII string buffer for interop.
dotnet/DDS_Core/Helpers/stringArray2x128.cs	Fixed-size 2x128 ASCII string buffer for interop.
dotnet/DDS_Core/Helpers/stringArray10xDebugView.cs	Debugger proxy helper for 10-row string buffers.
dotnet/DDS_Core/Helpers/stringArray10x10.cs	Fixed-size 10x10 ASCII string buffer for interop.
dotnet/DDS_Core/Helpers/string80.cs	Fixed-size 80-byte ASCII string buffer for interop.
dotnet/DDS_Core/Helpers/string106.cs	Fixed-size 106-byte ASCII string buffer for interop.
dotnet/DDS_Core/Helpers/SolverContextHandle.cs	SafeHandle wrapper for the native SolverContext pointer lifetime.
dotnet/DDS_Core/Helpers/SolveBoardResultExtensions.cs	Adds error-code-to-message helpers for DDS return codes.
dotnet/DDS_Core/Helpers/ResultsTable.cs	Adds a fixed 5x4 int buffer helper type for interop.
dotnet/DDS_Core/Helpers/intArray5xDebugView.cs	Debugger proxy helper for 5-row numeric buffers.
dotnet/DDS_Core/Helpers/intArray5x4.cs	Fixed-size 5x4 int buffer for interop.
dotnet/DDS_Core/Helpers/intArray53.cs	InlineArray wrapper for 53 ints (play-analysis tricks).
dotnet/DDS_Core/Helpers/intArray52.cs	InlineArray wrapper for 52 ints (play trace arrays).
dotnet/DDS_Core/Helpers/intArray5.cs	InlineArray wrapper for 5 ints.
dotnet/DDS_Core/Helpers/intArray3.cs	InlineArray wrapper for 3 ints.
dotnet/DDS_Core/Helpers/intArray200.cs	InlineArray wrapper for up to 200 ints (batch operations).
dotnet/DDS_Core/Helpers/intArray13.cs	InlineArray wrapper for 13 ints (future tricks arrays).
dotnet/DDS_Core/Helpers/IBuffer.cs	Interface used by debug-view helpers for row-to-string conversion.
dotnet/DDS_Core/Helpers/Global.cs	Small constant tables for contract formatting output.
dotnet/DDS_Core/Helpers/FourHands.cs	Fixed 4x4 uint buffer representing hands/suits card bitmasks.
dotnet/DDS_Core/DDS.cs	Main .NET wrapper class exposing legacy API calls + helper utilities.
dotnet/DDS_Core/DDS_Core.slnx	Adds a dedicated .NET solution including dds_native dependency.
dotnet/DDS_Core/DDS_Core.csproj	Adds .NET 8 library project configuration.
dotnet/DDS_Core/DataModel/SolverContext.cs	Managed SolverContext wrapper using SafeHandle and P/Invoke.
dotnet/DDS_Core/DataModel/SolverConfig.cs	Managed SolverConfig struct for native config interop.
dotnet/DDS_Core/DataModel/SolvedPlays.cs	Interop model for multiple solved play traces.
dotnet/DDS_Core/DataModel/SolvedPlay.cs	Interop model for a single solved play trace.
dotnet/DDS_Core/DataModel/SolvedBoards.cs	Interop model for multiple solved boards.
dotnet/DDS_Core/DataModel/PlayTracesPBN.cs	Interop model for multiple PBN play traces.
dotnet/DDS_Core/DataModel/PlayTracesBin.cs	Interop model for multiple binary play traces.
dotnet/DDS_Core/DataModel/PlayTracePBN.cs	Interop model for a PBN play trace.
dotnet/DDS_Core/DataModel/PlayTraceBin.cs	Interop model for a binary play trace.
dotnet/DDS_Core/DataModel/ParTextResults.cs	Interop model for par text results.
dotnet/DDS_Core/DataModel/ParResultsMasters.cs	Interop model for multi-side par results (master format).
dotnet/DDS_Core/DataModel/ParResultsMaster.cs	Interop model for par results master record and contracts.
dotnet/DDS_Core/DataModel/ParResultsDealers.cs	Interop model for dealer-oriented par results for both sides.
dotnet/DDS_Core/DataModel/ParResultsDealer.cs	Interop model for dealer par results.
dotnet/DDS_Core/DataModel/parResults.cs	Interop model for par scores/contracts strings (2-sided).
dotnet/DDS_Core/DataModel/FutureTricks.cs	Interop model for future tricks results.
dotnet/DDS_Core/DataModel/Enums and Constants/TTKind.cs	Managed enum mirroring native TT kind selection.
dotnet/DDS_Core/DataModel/Enums and Constants/Suit.cs	Managed suit enum.
dotnet/DDS_Core/DataModel/Enums and Constants/SolvingMode.cs	Managed solving-mode enum.
dotnet/DDS_Core/DataModel/Enums and Constants/SolveBoardResult.cs	Managed DDS return-code enum + docs.
dotnet/DDS_Core/DataModel/Enums and Constants/Hand.cs	Managed hand enum.
dotnet/DDS_Core/DataModel/Enums and Constants/DdsConstants.cs	Managed constants mirroring DDS limits.
dotnet/DDS_Core/DataModel/Enums and Constants/CardRanks.cs	Managed card-rank bitmask enum.
dotnet/DDS_Core/DataModel/DealPBN.cs	Interop model for PBN deal input.
dotnet/DDS_Core/DataModel/Deal.cs	Interop model for binary deal input.
dotnet/DDS_Core/DataModel/DdTablesResult.cs	Interop model for multiple DD-table results with indexing helper.
dotnet/DDS_Core/DataModel/ddTableResults.cs	Interop model for one DD-table result.
dotnet/DDS_Core/DataModel/DdTableDealsPBN.cs	Interop model for batch PBN DD-table deal inputs.
dotnet/DDS_Core/DataModel/DdTableDeals.cs	Interop model for batch binary DD-table deal inputs.
dotnet/DDS_Core/DataModel/DdTableDealPBN.cs	Interop model for single PBN DD-table deal input.
dotnet/DDS_Core/DataModel/ddTableDeal.cs	Interop model for single binary DD-table deal input.
dotnet/DDS_Core/DataModel/DDSInfo.cs	Interop model for library info (GetDDSInfo).
dotnet/DDS_Core/DataModel/ContractType.cs	Interop model for contract representation and formatting.
dotnet/DDS_Core/DataModel/BoardsPBN.cs	Interop model for batch PBN board solving input.
dotnet/DDS_Core/DataModel/Boards.cs	Interop model for batch binary board solving input.
dotnet/DDS_Core/DataModel/AllParResults.cs	Interop model for par results across multiple tables.
dotnet/DDS_Core/.cr/personal/Navigation/Code Places.xml	Adds IDE/user state file (should typically be excluded).
dotnet/DDS_Core_Demo/TestData.cs	Adds demo test data and validation helpers.
dotnet/DDS_Core_Demo/Properties/launchSettings.json	Enables mixed managed/native debugging for DDS_Core_Demo.
dotnet/DDS_Core_Demo/Program.cs	Adds demo program showcasing API usage + a benchmark mode.
dotnet/DDS_Core_Demo/DDS_Core_Demo.csproj	Adds .NET 8 console demo project referencing DDS_Core.
docs/dotnet_interface.md	Adds documentation describing the new .NET wrapper API.
.gitignore	Ignores additional .NET and IDE output/state directories.

Comments suppressed due to low confidence (2)

library/src/api/calc_par.hpp:67

• The SolverContext& overload is now declared with EXTERN_C, which changes it to C linkage and breaks the C++ ABI (symbol name changes) for existing consumers. Since this overload is not callable from C anyway (C++ reference parameter), keep it as normal C++ linkage and expose a separate C wrapper for P/Invoke instead.
  dotnet/DDS_Core/Helpers/ResultsTable.cs:59
• This file is missing the final closing } for the ResultsTable struct, which makes it syntactically invalid C#. Even if the file is currently excluded from compilation, leaving broken source in-repo is risky/confusing.