Per review: keep fall-through, claim, first-valid-wins, skipped-result
warning, malformed-result isolation, sanitization, and the end-to-end
synthetic-plugin test; drop the auxiliary variants. Compress the hooks.md
section to prose with a minimal return example.
Applies the batch-disposition SALVAGE conditions from #64231: the hook id
moves to the taxonomy transform-family name, and run-all-then-pick-first
dispatch now logs a runtime warning when a valid-but-losing classification
is skipped (the #64714 skipped-transform rule). Chaining semantics are
stated explicitly at the VALID_HOOKS entry, the dispatch helper docstring,
and the hooks.md catalog row and detail section.
