Remove audit/2026-03-15-01/ working notes

The multi-pass review notes (pass0–pass5 + triage) are redundant now
that every finding is resolved: 11 fixed in code, 3 dismissed, 1
documented, and the one triage missed (initilize typo) tracked + fixed
via #32. The findings live in the code, git history, and GH issues;
the per-pass working notes add nothing. Protofire's PDF audits under
audit/protofire/ are unaffected.

Author: thedavidmeister