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/blog_writer/router.py

@@ -66,6 +66,7 @@ class RecommendationItem(BaseModel):
 
 class SEOApplyRecommendationsRequest(BaseModel):
     title: str = Field(..., description="Current blog title")
+    introduction: str | None = Field(default=None, description="Current blog introduction text")
     sections: List[Dict[str, Any]] = Field(..., description="Array of sections with id, heading, content")
     outline: List[Dict[str, Any]] = Field(default_factory=list, description="Outline structure for context")
     research: Dict[str, Any] = Field(default_factory=dict, description="Research data used for the blog")
@@ -122,7 +123,7 @@ async def section_originality_tools(
             raise HTTPException(status_code=401, detail="User ID not found in authentication token")
 
         from services.intelligence.sif_integration import SIFIntegrationService
-        from services.intelligence.sif_agents import ContentGuardianAgent
+        from services.intelligence.agents.specialized import ContentGuardianAgent
 
         sif_service = SIFIntegrationService(user_id)
         intelligence = sif_service.intelligence_service