Consume an optional child-owned `(fd, inode)` capability before
multiprocessing or Trio child bootstrap begins runtime setup.
Deats,
- enter the netns before Trio patching and actor construction
- close the inherited FD before actor runtime startup
- preserve entry errors when descriptor cleanup also fails
- reject malformed FD values without closing unrelated descriptors
- cover multiprocessing and Trio ordering with real stand-in FDs
Prompt-IO: ai/prompt-io/opencode/20260828T012205Z_9ae7cd86_prompt_io.md
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))
Gud Boi