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/tests/test_nodes.py

@@ -0,0 +1,67 @@
+from unittest.mock import patch
+
+import pytest
+from httpx import AsyncClient
+
+TOKEN_HASH = "$2b$12$o/LWyvmBc978CNpSsHxcveXN0WqjAGW/gBR0.U.HURWbaYD3GCDqS"
+
+
+@pytest.fixture
+async def headers(client: AsyncClient):
+    with patch("app.api.routes.auth._load_credentials", return_value=("admin", TOKEN_HASH)):
+        res = await client.post("/api/v1/auth/login", json={"username": "admin", "password": "admin"})
+    token = res.json()["access_token"]
+    return {"Authorization": f"Bearer {token}"}
+
+
+async def test_list_nodes_empty(client: AsyncClient, headers: dict):
+    res = await client.get("/api/v1/nodes/", headers=headers)
+    assert res.status_code == 200
+    assert res.json() == []
+
+
+async def test_create_node(client: AsyncClient, headers: dict):
+    payload = {"type": "server", "label": "My Server", "ip": "192.168.1.10", "status": "unknown"}
+    res = await client.post("/api/v1/nodes/", json=payload, headers=headers)
+    assert res.status_code == 201
+    data = res.json()
+    assert data["label"] == "My Server"
+    assert data["ip"] == "192.168.1.10"
+    assert "id" in data
+
+
+async def test_get_node(client: AsyncClient, headers: dict):
+    create = await client.post("/api/v1/nodes/", json={"type": "router", "label": "Router", "status": "online"}, headers=headers)
+    node_id = create.json()["id"]
+    res = await client.get(f"/api/v1/nodes/{node_id}", headers=headers)
+    assert res.status_code == 200
+    assert res.json()["id"] == node_id
+
+
+async def test_get_node_not_found(client: AsyncClient, headers: dict):
+    res = await client.get("/api/v1/nodes/nonexistent-id", headers=headers)
+    assert res.status_code == 404
+
+
+async def test_update_node(client: AsyncClient, headers: dict):
+    create = await client.post("/api/v1/nodes/", json={"type": "server", "label": "Old", "status": "unknown"}, headers=headers)
+    node_id = create.json()["id"]
+    res = await client.patch(f"/api/v1/nodes/{node_id}", json={"label": "New", "ip": "10.0.0.1"}, headers=headers)
+    assert res.status_code == 200
+    assert res.json()["label"] == "New"
+    assert res.json()["ip"] == "10.0.0.1"
+
+
+async def test_delete_node(client: AsyncClient, headers: dict):
+    create = await client.post("/api/v1/nodes/", json={"type": "switch", "label": "Switch", "status": "unknown"}, headers=headers)
+    node_id = create.json()["id"]
+    res = await client.delete(f"/api/v1/nodes/{node_id}", headers=headers)
+    assert res.status_code == 204
+    assert (await client.get(f"/api/v1/nodes/{node_id}", headers=headers)).status_code == 404
+
+
+async def test_list_nodes_returns_all(client: AsyncClient, headers: dict):
+    for i in range(3):
+        await client.post("/api/v1/nodes/", json={"type": "generic", "label": f"Node {i}", "status": "unknown"}, headers=headers)
+    res = await client.get("/api/v1/nodes/", headers=headers)
+    assert len(res.json()) == 3