Release 0.15.3 with public truth reset

[danielgwilson]

What changed

• align the README, contributor ramp, current goals, architecture, contracts, fixtures, and state trackers with shipped behavior
• keep dated design and proof packets unchanged; add current-status amendments beside them
• distinguish core capability proof, real-application study subjects, and adopter deletion proof
• make generated dry-run/live claims describe only the current run
• document the closed six-descriptor first-party actor registry and route-owned terminal lifecycle
• accept both official GitHub noreply email forms while rejecting malformed usernames and lookalike domains
• stage humanish@0.15.3 because the corrected public docs ship in the npm package

Validation

• secret-backed pnpm release:check
• 1,044 tests passed; 10 skipped
• typecheck and build passed
• public-surface scan checked 447 text files and one allowlisted binary asset
• skill validation passed
• npm pack dry-run produced humanish@0.15.3 with 205 files
• focused hostile review found no material blocker
• dated designs and receipts remain byte-unchanged

No release tag or npm publication is part of this PR; those remain explicit maintainer actions after merge.