feat(knowledge-flywheel): add Phase 3 Knowledge Flywheel — AI analysis, review queue, analytics

Phase 3 implementation:
- AI session analysis service that generates flow proposals from resolved sessions
- APScheduler job for batch processing pending analyses (max_instances=1)
- Knowledge gap detection (weak options, high escalation signals)
- Flow proposals CRUD with team admin review workflow (approve/edit/dismiss/reject)
- FlowPilot analytics dashboard with confidence tiers, PSA metrics, knowledge gaps
- In-session script generator component
- Review queue page with filtering and proposal detail panel

Bug fixes from review (12 total):
- Fix "Edit & Publish" navigating to non-existent /editor/new route
- Hide Approve button for enhancement proposals (require Edit & Publish)
- Add max_instances=1 to scheduler to prevent TOCTOU race
- Fix eventual_success case() double-counting failed retries
- Add tree_structure validation before creating tree from proposal
- Simplify script generator rendering condition
- Add severity style fallback, toFixed on rates, Link instead of <a href>
- Add toast.warning on dismiss failure, fix dedup for domain-less sessions
- Cast Decimal to int in knowledge gap evidence dicts

Also updates CLAUDE.md with lessons 67-71 and Phase 3 project structure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/main.py

@@ -190,6 +190,17 @@ async def lifespan(app: FastAPI):
         replace_existing=True,
     )
 
+    # Knowledge Flywheel analysis (every 5 minutes)
+    from app.services.knowledge_flywheel_scheduler import process_pending_analyses
+    scheduler.add_job(
+        process_pending_analyses,
+        trigger="interval",
+        minutes=5,
+        id="knowledge_flywheel_analysis",
+        replace_existing=True,
+        max_instances=1,
+    )
+
     # Auto-seed trees in background on PR environments
     seed_task = None
     if settings.SEED_ON_DEPLOY: