running-process-platform-internal

Internal, published host-mechanics boundary for running-process. Its public surface is intentionally small; product policy remains in the caller crates.

Deprecated 4.x PTY trait accessors remain source-compatible until 5.0, but platform mechanics never consume their primitive values. Native PTY control state must stay captured inside concrete operations; the neutral facade may not introduce descriptor/HANDLE payload structs or tokens.

src/lib.rs is the only host selector. Neutral capability indexes live in src/platform/; their private Windows, Linux, and macOS implementations are selected behind that boundary.