feat(docs): add broken link validation script

Co-authored-by: PR0M3TH3AN <[email protected]>

src/todo/TODO_2026-02-20T02-09-00Z.md

@@ -13,8 +13,8 @@ Executing prompt: `src/prompts/daily/docs-agent.md`
 
 ## Pending
 - [ ] Verify package.json scripts against docs.
-- [ ] Check for broken links to missing docs.
 
 ## Completed
+- [x] Check for broken links to missing docs.
 - [x] Initial audit of README.md and CONTRIBUTING.md.
 - [x] Update docs-agent.md to remove stale audit targets.