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/schemas/script_template.py

@@ -116,7 +116,8 @@ class ScriptTemplateDetail(ScriptTemplateListItem):
 class ScriptGenerateRequest(BaseModel):
     template_id: UUID
     parameters: dict[str, Any]
-    session_id: Optional[UUID] = None
+    session_id: Optional[UUID] = None  # Legacy tree-based session
+    ai_session_id: Optional[UUID] = None  # FlowPilot AI session
 
 class ScriptGenerateResponse(BaseModel):
     id: UUID