docs: cap cross-model Codex review at 5 rounds per PR, then escalate (#791)

Add escalation trigger #4: when a PR is gated by a Codex cross-model review,
run at most 5 fix->re-review rounds on that PR; if not clean after the 5th,
stop and ask the human. Per-PR counter, resets each PR. Prevents endless
whack-a-mole on heuristic-style findings (e.g. the phrase-position tuning on
#786) while keeping the gate meaningful.

Related: Spec 077 (specs/077-scanner-simplification)

Author: Dumbris

CLAUDE.md

@@ -18,6 +18,7 @@ Only halt and ask a human IF:
 1. You need destructive data operations or to delete core proxy logic that cannot be mocked.
 2. A required environment variable is missing from `.env` and cannot be mocked for the task's scope.
 3. You are stuck in an error loop for the same `go test` failing after 5 consecutive attempts.
+4. **Cross-model (Codex) review round cap — per PR:** when a PR is gated by a cross-model Codex review, run at most **5 fix→re-review rounds on that PR**. If Codex has not returned a clean verdict after the 5th round, STOP and ask the human how to proceed (do not auto-run round 6). The counter is per-PR and resets for each new PR. (Verify each Codex finding is genuine before fixing — Codex can false-positive; a round only counts when you push a fix and re-review.)
 
 ## Project Overview