Agent Skills: post-implementation-review

Hub for the broad post-implementation review and second-read pass after an implementation: list every touched file as an ASCII tree, mentally inline helpers, audit dead paths and stale imports, name invariant owners, sanity-check API shape and naming, and delegate to focused review skills as needed. Use after finishing an implementation, before final response, or when the user says 'post-implementation review', 'review what you just did', 'second pass', or 'final sweep'.