feat(settings): server global brightness and Wi-Fi driver resync

- Serve GET /settings as JSON by removing duplicate HTML route (use /settings/page for the standalone UI).

- Save global_brightness via PUT; broadcast to connected drivers; push saved level when outbound WS connects.

- Zones UI loads brightness from GET /settings only (no localStorage).

- Bump led-driver submodule for settings.save on brightness with save flag.

- Extend API doc and endpoint tests for global_brightness.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_endpoints_pytest.py

@@ -347,6 +347,15 @@ def test_settings_controller(server):
     resp = c.put(f"{base_url}/settings/settings", json={"wifi_channel": 12})
     assert resp.status_code == 400
 
+    resp = c.put(f"{base_url}/settings/settings", json={"global_brightness": 42})
+    assert resp.status_code == 200
+    resp = c.get(f"{base_url}/settings")
+    assert resp.status_code == 200
+    assert resp.json().get("global_brightness") == 42
+
+    resp = c.put(f"{base_url}/settings/settings", json={"global_brightness": 300})
+    assert resp.status_code == 400
+
 
 def test_profiles_presets_zones_endpoints(server, monkeypatch):
     c: requests.Session = server["client"]