fix: all lint errors, test + lint pre-commit passing

Frontend:
- Split nodeTypes/edgeTypes into separate .ts files (react-refresh)
- Remove setState-in-effect in NodeModal (key prop reset)
- Fix handleSave accessed before declaration (useRef pattern)
- Exclude src/components/ui/** from eslint (shadcn generated)
- Use defineConfig from vitest/config for test type support

Backend:
- ruff --fix: sort imports, datetime.UTC alias
- Raise line-length to 120, ignore E501 in tests
- Break long update_node/update_edge signatures
- pyproject.toml: per-file-ignores for tests

backend/app/api/routes/canvas.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timezone
+from datetime import UTC, datetime
 
 from fastapi import APIRouter, Depends
 from sqlalchemy import select
@@ -34,7 +34,7 @@ async def save_canvas(body: CanvasSaveRequest, db: AsyncSession = Depends(get_db
     state = await db.get(CanvasState, 1)
     if state:
         state.viewport = body.viewport
-        state.saved_at = datetime.now(timezone.utc)
+        state.saved_at = datetime.now(UTC)
     else:
         db.add(CanvasState(id=1, viewport=body.viewport))
 

backend/app/api/routes/edges.py

@@ -35,7 +35,9 @@ async def delete_edge(edge_id: str, db: AsyncSession = Depends(get_db), _: str =
 
 
 @router.patch("/{edge_id}", response_model=EdgeResponse)
-async def update_edge(edge_id: str, body: EdgeUpdate, db: AsyncSession = Depends(get_db), _: str = Depends(get_current_user)):
+async def update_edge(
+    edge_id: str, body: EdgeUpdate, db: AsyncSession = Depends(get_db), _: str = Depends(get_current_user)
+):
     edge = await db.get(Edge, edge_id)
     if not edge:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Edge not found")

backend/app/api/routes/nodes.py

@@ -34,7 +34,9 @@ async def get_node(node_id: str, db: AsyncSession = Depends(get_db), _: str = De
 
 
 @router.patch("/{node_id}", response_model=NodeResponse)
-async def update_node(node_id: str, body: NodeUpdate, db: AsyncSession = Depends(get_db), _: str = Depends(get_current_user)):
+async def update_node(
+    node_id: str, body: NodeUpdate, db: AsyncSession = Depends(get_db), _: str = Depends(get_current_user)
+):
     node = await db.get(Node, node_id)
     if not node:
         raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="Node not found")