Additional documentation for the SDK.

Building — prerequisites, build scripts, CMake presets, vcpkg, Docker, integration into your CMake project, troubleshooting.
Logging — compile-time vs runtime filtering, log levels, custom sinks (file, JSON, ROS2 RCLCPP_* macros).
Tracing — Chromium-format performance traces, viewing in chrome://tracing and Perfetto.
Testing — unit, integration, and stress test suites; env vars; token-helper script for local livekit-server --dev runs.
Developer tools — clang-tidy, clang-format, valgrind, Doxygen, pre-commit hook, Rust submodule recovery tips.