BAML Ruby V1 bridge

This directory contains private runtime plumbing for generated Ruby/Sorbet SDKs. Generated code calls:

Baml::Bridge.initialize!(compiled_program_bytes)

The bridge loads the absolute library path in BAML_RUNTIME_PATH, validates the complete V1 C table, requires an exact canonical BAML toolchain version, registers Baml::Bridge as bridge language 10 with its stamped bridge runtime version, and initializes one exact generated program per process.

This checkpoint deliberately has no public gem packaging, runtime discovery, download, unload, reset, or project-switching API. Packaging and the public gem name remain release work.