v1.5.19

• Preserve sole root and tail-called Go frames across coroutine yields so Resume and ResumeInto report ResumeYield instead of false successful completion.
• Return resume arguments correctly through direct Go entry functions, Lua tail calls, nested coroutine.resume, and coroutine.wrap.
• Restore parent/current-thread state and terminate the child when a resume encounters a canceled context.
• Contain invalid yielded-thread state with an explicit run error and consistent thread cleanup.
• Add regression coverage across default, 128-slot, and 384-slot registries, forced registry growth, repeated thread reuse, zero/one/multiple resume values, and cancellation before start or after yield.
• Keep existing tail-call and coroutine performance stable with unchanged allocation counts.