feat: ContentGuardianAgent, onboarding UX, Team Activity action wiring, docs, agent help modal

ContentGuardianAgent consolidation:
- Merge 3 duplicate classes into single source in specialized/content_guardian.py
- Watchdog audit_committee() with heuristic scoring, coverage gaps, overlaps, alerts
- Remove misleading rejection_rate() helper; use acceptance_rate directly
- Integrate audit + alerts + trend signals into today_workflow_service.py

Team Activity page:
- QualityAuditPanel: health ring, per-agent critiques, coverage gaps, overlaps
- TrendSignalsPanel: opportunity cards with urgency/impact/coverage bars
- AlertBanner: persistent dismiss via POST /alerts/{id}/mark-read
- AgentHelpModal: dialog showing all 8 agents with descriptions, tools, schedule
- QualityAuditPanel action buttons: Fill gap -> /content-planning, Resolve overlap, View CTA on alerts/issues
- TrendSignalsPanel action buttons: Create content from this trend -> /blog-writer with trend context state

Onboarding system:
- Step 4 validation: no auto-pass via basic_ready; requires persona data or explicit progression
- Step 5 validation: logs warning on auto-pass without integration data
- OnboardingCompletionService: single DB session, transactional task creation, upsert pattern
- Business-without-website: nullable website_url on SIFIndexingTask and MarketTrendsTask
- DeepCompetitorAnalysisExecutor: 5-min timeout, 10-competitor cap, asyncio.wait_for
- Persona generation: async with 30s timeout, falls back to scheduler
- OnboardingProgressService.reset_onboarding(): resets session + pauses all DB tasks
- OnboardingControlService.reset_onboarding(): also cancels APScheduler jobs
- FinalStep TaskSchedulingPanel: shows scheduled/failed tasks after completion, 8s auto-redirect
- onboarding_completed agent activity event logged to feed

Documentation:
- docs-site/features/onboarding/: overview, steps, scheduler-tasks, technical-reference (4 pages)
- docs-site/mkdocs.yml: added Onboarding System nav section
- docs-site/features/sif-agents/: overview, agent-directory, committee-system, content-guardian (4 pages)
- docs-site/features/team-activity/: overview, quality-audit, trend-signals, alert-system (4 pages)
- docs-site/features/todays-workflow/: updated overview, technical-architecture, workflow-guide, api-reference

backend/api/onboarding_utils/onboarding_control_service.py

@@ -50,22 +50,40 @@ class OnboardingControlService:
                 db.close()
     
     async def reset_onboarding(self, current_user: Dict[str, Any]) -> Dict[str, Any]:
-        """Reset the onboarding progress for a specific user."""
+        """Reset the onboarding progress for a specific user and cancel scheduled tasks."""
         try:
             from services.onboarding.progress_service import OnboardingProgressService
             user_id = str(current_user.get('clerk_user_id') or current_user.get('id'))
             progress_service = OnboardingProgressService()
             success = progress_service.reset_onboarding(user_id)
 
-            if success:
-                return {
-                    "message": "Onboarding progress reset successfully",
-                    "current_step": 1,
-                    "started_at": None,
-                    "user_id": user_id
-                }
-            else:
+            if not success:
                 raise HTTPException(status_code=500, detail="Failed to reset onboarding progress")
+
+            # Cancel APScheduler one-shot jobs for this user
+            cancelled_jobs = []
+            try:
+                from services.scheduler import get_scheduler
+                scheduler = get_scheduler()
+                for job_id_suffix in ["research_persona", "facebook_persona"]:
+                    job_id = f"{job_id_suffix}_{user_id}"
+                    try:
+                        scheduler.scheduler.remove_job(job_id)
+                        cancelled_jobs.append(job_id)
+                    except Exception:
+                        pass
+            except Exception as e:
+                logger.warning(f"Could not cancel APScheduler jobs for user {user_id}: {e}")
+
+            return {
+                "message": "Onboarding progress reset successfully",
+                "current_step": 1,
+                "started_at": None,
+                "user_id": user_id,
+                "cancelled_jobs": cancelled_jobs if cancelled_jobs else None,
+            }
+        except HTTPException:
+            raise
         except Exception as e:
             logger.error(f"Error resetting onboarding: {str(e)}")
             raise HTTPException(status_code=500, detail="Internal server error")