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.

backend/app/db/engine.py

@@ -21,9 +21,14 @@ _engine_kwargs: dict = dict(
 )
 
 if _is_sqlite:
-    _engine_kwargs["connect_args"] = {"timeout": 30}
-    _engine_kwargs["pool_size"] = 1
-    _engine_kwargs["max_overflow"] = 0
+    _engine_kwargs["connect_args"] = {"timeout": 60, "check_same_thread": False}
+    # NullPool: each session gets its own connection.
+    # Combined with WAL mode, this allows concurrent reads while a write is in progress.
+    from sqlalchemy.pool import NullPool
+    _engine_kwargs["poolclass"] = NullPool
+else:
+    _engine_kwargs["pool_size"] = 5
+    _engine_kwargs["max_overflow"] = 10
 
 engine = create_async_engine(settings.DATABASE_URL, **_engine_kwargs)
 
@@ -34,7 +39,7 @@ def _set_sqlite_pragmas(dbapi_conn, connection_record):
     if _is_sqlite:
         cursor = dbapi_conn.cursor()
         cursor.execute("PRAGMA journal_mode=WAL")
-        cursor.execute("PRAGMA busy_timeout=5000")
+        cursor.execute("PRAGMA busy_timeout=30000")
         cursor.execute("PRAGMA synchronous=NORMAL")
         cursor.close()
 
@@ -46,6 +51,10 @@ async_session_factory = async_sessionmaker(
 )
 
 
+# Alias expected by other modules
+async_session = async_session_factory
+
+
 class Base(DeclarativeBase):
     """Base class for all ORM models."""
     pass
@@ -71,5 +80,5 @@ async def init_db() -> None:
 
 
 async def dispose_db() -> None:
-    """Dispose of the engine connection pool."""
-    await engine.dispose()
+    """Dispose of the engine on shutdown."""
+    await engine.dispose()