feat: Add Playbook Manager, Saved Searches, and Timeline View components

- Implemented PlaybookManager for creating and managing investigation playbooks with templates.
- Added SavedSearches component for managing bookmarked queries and recurring scans.
- Introduced TimelineView for visualizing forensic event timelines with zoomable charts.
- Enhanced backend processing with auto-queued jobs for dataset uploads and improved database concurrency.
- Updated frontend components for better user experience and performance optimizations.
- Documented changes in update log for future reference.

_fix_import_datasets.py

@@ -0,0 +1,7 @@
+from pathlib import Path
+p=Path(r'd:/Projects/Dev/ThreatHunt/backend/app/api/routes/datasets.py')
+t=p.read_text(encoding='utf-8')
+if 'from app.db.models import ProcessingTask' not in t:
+    t=t.replace('from app.db import get_db\n', 'from app.db import get_db\nfrom app.db.models import ProcessingTask\n')
+p.write_text(t, encoding='utf-8')
+print('added ProcessingTask import')