Add SQLite project database + ComfyUI connector nodes

- db.py: ProjectDB class with SQLite schema (projects, data_files,
  sequences, history_trees), WAL mode, CRUD, import, and query helpers
- api_routes.py: REST API endpoints on NiceGUI/FastAPI for ComfyUI
  to query project data over the network
- project_loader.py: ComfyUI nodes (ProjectLoaderDynamic, Standard,
  VACE, LoRA) that fetch data from NiceGUI REST API via HTTP
- web/project_dynamic.js: Frontend JS for dynamic project loader node
- tab_projects_ng.py: Projects management tab in NiceGUI UI
- state.py: Added db, current_project, db_enabled fields
- main.py: DB init, API route registration, projects tab
- utils.py: sync_to_db() dual-write helper
- tab_batch_ng.py, tab_raw_ng.py, tab_timeline_ng.py: dual-write
  sync calls after save_json when project DB is enabled
- __init__.py: Merged project node class mappings
- tests/test_db.py: 30 tests for database layer
- tests/test_project_loader.py: 17 tests for ComfyUI connector nodes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

state.py

@@ -17,6 +17,11 @@ class AppState:
     live_toggles: dict = field(default_factory=dict)
     show_comfy_monitor: bool = True
 
+    # Project DB fields
+    db: Any = None
+    current_project: str = ""
+    db_enabled: bool = False
+
     # Set at runtime by main.py / tab_comfy_ng.py
     _render_main: Any = None
     _load_file: Callable | None = None