docs(nap): add archiveDecisions() contract comment

[diberry]

Minimal JSDoc contract for archiveDecisions() documenting entry format, invariants, thresholds, and return behavior.

Closes #37

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[diberry]

✅ APPROVED

Minimal and correct:

• Single commit: docs(nap): add archiveDecisions() contract comment
• Only JSDoc comment added to archiveDecisions() in nap.ts (lines 311-336)
• No code changes, no unrelated files
• Comment accurately documents the function's contract, invariants, threshold behavior, and archival strategy

All criteria met for issue #37.

[diberry]

✅ APPROVED

Quality gate verification for PR #59 (docs(nap): add archiveDecisions() contract comment):

• ✅ Exactly 1 commit on branch (squad/37-nap-jsdoc)
• ✅ Only 3 files changed (expected scribe charter + template + nap.ts)
• ✅ Comment-only change to nap.ts — zero functional changes
• ✅ JSDoc contract for \�rchiveDecisions()\ is thorough (invariants, threshold, strategy, parameters, return value all documented)
• ✅ No junk files

Ready to merge.

[diberry]

Retargeted to bradygaster#648