Fix production issues: add matplotlib dep, fix get_db calls, resolve ESLint

- Add matplotlib>=3.7.0 to requirements-podcast.txt (B-roll requires it)
- Fix research.py and exa_provider.py using get_session_for_user() instead of broken Depends(get_db)
- Fix BrollInfoPanel.tsx: call useScriptEditor hook unconditionally
- Add debug logging to avatar endpoint for troubleshooting

backend/api/onboarding_utils/step4_asset_routes.py

@@ -86,6 +86,8 @@ async def get_latest_avatar(
     try:
         user_id = _extract_user_id(current_user)
         
+        logger.info(f"[latest-avatar] Looking for avatar for user_id: {user_id}")
+        
         # Search for assets that are either:
         # 1. Saved with source_module=BRAND_AVATAR_GENERATOR (new)
         # 2. Saved with source_module=STORY_WRITER but have metadata category='brand_avatar' (legacy)
@@ -100,6 +102,8 @@ async def get_latest_avatar(
             ])
         ).order_by(desc(ContentAsset.created_at)).limit(50).all()
         
+        logger.info(f"[latest-avatar] Found {len(candidates)} candidate(s)")
+        
         asset = None
         for candidate in candidates:
             # Check for direct match (new assets)