Add SingleInstanceManager: mutex-based single instance with named-pipe window activation

[Copilot]

Adds SingleInstanceManager to LuYao.Threading — a static helper that enforces single-process execution via a global named mutex and uses a named pipe to signal the existing instance to activate its window.

Implementation

• src/LuYao.Common/Threading/SingleInstanceManager.cs

  • Global mutex name: Global\LuYao.SingleInstance[{uid}] where uid is the MD5 hash of Environment.ProcessPath (NET6+) / AppContext.BaseDirectory — unique per application binary
  • Pipe name: LuYaoSI{uid} (no backslash, safe across all pipe implementations)
  • First instance starts a long-running background server thread that listens for ActivateWindow commands and fires ActivateWindowRequested
  • Subsequent instances connect to the pipe, send ActivateWindow, then Environment.Exit(0)
  • ReleaseLock() allows explicit teardown (e.g. for restart scenarios)
  • Cross-framework: #if NETFRAMEWORK guards for WaitForConnectionAsync and #if NET45 / #if NET6_0_OR_GREATER guards for AppContext/Environment.ProcessPath

• tests/LuYao.Common.UnitTests/Threading/SingleInstanceManagerTests.cs — covers ReleaseLock idempotency, event subscribe/unsubscribe, and named pipe round-trip

• README.zh-CN.md / README.en.md — added section 13 documenting SingleInstanceManager

Usage

// Program startup
SingleInstanceManager.EnsureSingleInstance();

// Subscribe before or after — fired when a second instance starts
SingleInstanceManager.ActivateWindowRequested += (_, _) =>
{
    mainWindow.Activate();
    mainWindow.WindowState = WindowState.Normal;
};

[Soar360]

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