fix: resolve test pollution from freeze_saves and fix os_listener toggle

- Add unfreeze_saves() to base_store.py and call it in e2e cleanup.
  The backup restore flow calls freeze_saves() which sets a module-level
  flag that silently disables all store _save() calls. Without reset,
  this poisoned all subsequent persistence tests (9 failures).
- Fix os_listener toggle to use toggle-switch/toggle-slider CSS classes
  instead of nonexistent switch/slider classes (was showing plain checkbox).
- Add mandatory test run to CLAUDE.md pre-commit checks.

All 341 tests now pass.

CLAUDE.md

@@ -76,13 +76,14 @@ Plain HTML selects break the visual consistency of the UI.
 
 ## Pre-Commit Checks (MANDATORY)
 
-Before every commit, run the relevant linters and fix any issues:
+Before every commit, run the relevant checks and fix any issues:
 
 - **Python changes**: `cd server && ruff check src/ tests/ --fix`
 - **TypeScript changes**: `cd server && npx tsc --noEmit && npm run build`
 - **Both**: Run both checks
+- **Always run tests**: `cd server && py -3.13 -m pytest tests/ --no-cov -q` — all tests MUST pass before committing. Do NOT commit code that fails tests.
 
-Do NOT commit code that fails linting. Fix the issues first.
+Do NOT commit code that fails linting or tests. Fix the issues first.
 
 ## General Guidelines
 

server/src/wled_controller/storage/base_store.py

@@ -24,6 +24,12 @@ def freeze_saves() -> None:
     logger.info("Store saves frozen — awaiting server restart")
 
 
+def unfreeze_saves() -> None:
+    """Re-enable store saves (used in tests to reset after restore flow)."""
+    global _saves_frozen
+    _saves_frozen = False
+
+
 class EntityNotFoundError(ValueError):
     """Raised when an entity is not found in the store."""
     pass

server/src/wled_controller/templates/modals/css-editor.html

@@ -381,9 +381,9 @@
                             <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?" data-i18n-aria-label="aria.hint">?</button>
                         </div>
                         <small class="input-hint" style="display:none" data-i18n="color_strip.notification.os_listener.hint">When enabled, this source automatically fires when a desktop notification appears (Windows toast / Linux D-Bus). Requires the app to have notification access permission.</small>
-                        <label class="switch">
+                        <label class="toggle-switch">
                             <input type="checkbox" id="css-editor-notification-os-listener">
-                            <span class="slider"></span>
+                            <span class="toggle-slider"></span>
                         </label>
                     </div>
 

server/tests/e2e/conftest.py

@@ -46,6 +46,11 @@ def client(_test_client):
 
 def _clear_stores():
     """Remove all entities from all stores for test isolation."""
+    # Reset the saves-frozen flag that freeze_saves() sets during restore flows.
+    # Without this, subsequent tests can't persist data because _save() is a no-op.
+    from wled_controller.storage.base_store import unfreeze_saves
+    unfreeze_saves()
+
     from wled_controller.api import dependencies as deps
 
     store_clearers = [