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.

_aup_extend_scanhit_api.py

@@ -0,0 +1,32 @@
+from pathlib import Path
+p=Path(r'd:/Projects/Dev/ThreatHunt/backend/app/api/routes/keywords.py')
+t=p.read_text(encoding='utf-8')
+old='''class ScanHit(BaseModel):
+    theme_name: str
+    theme_color: str
+    keyword: str
+    source_type: str
+    source_id: str | int
+    field: str
+    matched_value: str
+    row_index: int | None = None
+    dataset_name: str | None = None
+'''
+new='''class ScanHit(BaseModel):
+    theme_name: str
+    theme_color: str
+    keyword: str
+    source_type: str
+    source_id: str | int
+    field: str
+    matched_value: str
+    row_index: int | None = None
+    dataset_name: str | None = None
+    hostname: str | None = None
+    username: str | None = None
+'''
+if old not in t:
+    raise SystemExit('ScanHit pydantic model block not found')
+t=t.replace(old,new)
+p.write_text(t,encoding='utf-8')
+print('extended API ScanHit model with hostname+username')