feat(analysis): add check_analysis_approved QG with stakeholder approval requirement

- stages.py: QG renamed to check_analysis_approved (requires :approved: comment)
- qg/checks.py: new check_analysis_approved verifies files + Plane :approved: comment
- launcher.py: skip auto-advance for analysis stage (requires human approval)
- plane.py: route check_analysis_approved in _try_advance_stage
- docs/ARCHITECTURE.md: updated QG table and flow description

src/agents/launcher.py

@@ -257,8 +257,8 @@ class AgentLauncher:
             # Run QG check if defined
             if qg_name and qg_name in QG_CHECKS:
                 check_fn = QG_CHECKS[qg_name]
-                if qg_name == "check_review_approved":
-                    # Skip — handled by PR webhook
+                if qg_name in ("check_review_approved", "check_analysis_approved"):
+                    # Skip — requires human approval (handled by webhook comment handler)
                     return
                 elif qg_name == "check_ci_green":
                     passed, reason = check_fn(repo, branch)