Toolchain 0.5.0

Toolchain 0.5.0 makes SDK header publication explicit and runs Web validation through the standard project workflow.

Main update:

Projects run tests and benchmarks with --config=web while ordinary Web binaries retain the hosted SDK platform. Headers remain public by default; implementation headers define TOOLCHAIN_PRIVATE_HEADER as 1 locally. Packaging omits marked files and rejects public headers that depend on them.

Features:

• Run :tests and :benchmarks under the standard Web configuration through the pinned Emscripten and Node toolchain.
• Select a project's static runtime for standalone Web validation while preserving its ordinary source linkage.
• Configure Emscripten thread support independently for validation programs.
• Mark implementation-only headers at their declaration without adding Bazel wrapper targets or path conventions.
• Exclude marked headers from SDK archives and component metadata, and require published header dependencies to remain public.
• Apply source path and namespace checks to unmarked headers under every source directory.
• Keep placement construction compatible with foreign standard-library headers while retaining the standalone header surface.

The 0.5.0 hotpatch supports publishing several SDK modules from one repository. Auxiliary packages preserve the primary module's static validation runtime.