Motivation

• The repository's mdBook lacked concrete guidance for building the SDK with CMake and for using vcpkg, leaving build/cmake.html and its vcpkg subpage empty.
• Provide clear, reproducible instructions for developers and CI consumers covering source builds, installable package usage, FetchContent integration, and vcpkg manifest/overlay flows.
• Align documentation with the repository's existing CI and packaging conventions (triplets, overlay port, postgres feature, binary caching, and troubleshooting).

Description

• Added book/src/build/cmake.md with requirements, configure/build/test commands, CMake options, generated protobuf header location, install-as-package examples, FetchContent usage, exported targets, curated examples, and platform notes.
• Added book/src/build/vcpkg.md with vcpkg prerequisites, manifest-mode build instructions, Visual Studio/multi-config guidance, triplet usage, overlay-port consumption, the postgres-store feature, classic-mode smoke install steps, binary caching tips, and troubleshooting hints.
• Validated the mdBook build to ensure pages render and are discoverable from the book navigation.