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/services/research/google_search_service.py

@@ -76,7 +76,7 @@ class GoogleSearchService:
             logger.info(f"Searching for: {search_query}")
             
             # Perform the search
-            search_results = await self._perform_search(search_query, max_results)
+            search_results = await self.perform_search(search_query, max_results)
             
             # Process and rank results
             processed_results = await self._process_search_results(search_results, topic, industry)
@@ -140,13 +140,16 @@ class GoogleSearchService:
         
         return " ".join(query_components)
     
-    async def _perform_search(self, query: str, max_results: int) -> List[Dict[str, Any]]:
+    async def perform_search(self, query: str, max_results: int, **overrides) -> List[Dict[str, Any]]:
         """
         Perform the actual Google Custom Search API call.
         
         Args:
             query: The search query to execute
             max_results: Maximum number of results to return
+            **overrides: Override or disable default params.
+                         Pass `param=None` to remove a default param entirely.
+                         Pass `param=value` to override its value.
             
         Returns:
             Raw search results from Google API
@@ -158,8 +161,15 @@ class GoogleSearchService:
             "num": min(max_results, 10),  # Google CSE max is 10 per request
             "dateRestrict": "m1",  # Last month
             "sort": "date",  # Sort by date for current information
-            "safe": "active"  # Safe search for professional content
+            "safe": "active",  # Safe search for professional content
         }
+        # Apply overrides: None removes the key, non-None overrides the value
+        if overrides:
+            for k, v in overrides.items():
+                if v is None:
+                    params.pop(k, None)
+                else:
+                    params[k] = v
         
         async with aiohttp.ClientSession() as session:
             async with session.get(self.base_url, params=params) as response:
@@ -477,7 +487,7 @@ class GoogleSearchService:
         try:
             # Perform a simple test search
             test_query = "AI technology trends 2024"
-            test_results = await self._perform_search(test_query, 1)
+            test_results = await self.perform_search(test_query, 1)
             
             return {
                 "status": "success",