feat: add E2E tests for device creation and account management

10 E2E tests using NiceGUI's User fixture:
- Device creation flow and name validation
- Password change (success, wrong current, mismatch, too short)
- API token creation, TOTP registration, invalid code rejection
- Account deletion with email confirmation

Tests live in tests/e2e/ with a separate conftest that loads the
NiceGUI testing plugin. CI runs unit and E2E tests as separate steps.

.forgejo/workflows/release.yml

@@ -40,8 +40,11 @@ jobs:
       - name: Install dependencies
         run: uv sync
 
-      - name: Run tests
-        run: uv run pytest -v --tb=short
+      - name: Run unit tests
+        run: uv run pytest tests/ --ignore=tests/e2e -v --tb=short
+
+      - name: Run E2E tests
+        run: uv run pytest tests/e2e/ -v --tb=short
 
   release:
     needs: test