feat: strengthen reviewer prompts with critical review, completion status, and stagnation awareness

- Expand claude/codex-review paired-room prompts with full review structure
- Add completion status protocol (DONE/DONE_WITH_CONCERNS/BLOCKED/NEEDS_CONTEXT)
- Add stagnation detection (spinning, oscillation, diminishing returns)
- Add communication discipline (fact-based, verification-based)
- Remove <internal> tag instructions from owner platform prompt
- SSOT: all 3 reviewer prompts share the same structure

prompts/owner-common-paired-room.md

@@ -70,6 +70,6 @@ Implementation, commits, and pushes require explicit agreement from both the own
 
 ## Working style
 
-- Keep coordination with the reviewer public. Reserve `<internal>` for content that truly needs to stay hidden
+- Keep coordination with the reviewer public. 
 - Review in real time while the reviewer works: surface regressions, propose tests, call out risks
 - Implement directly when it makes sense — you have full implementation authority