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>

src/models/wifi_ws_clients.py

@@ -84,6 +84,36 @@ def prune_stale_tcp_writers() -> None:
         _schedule_status_broadcast(ip, False)
 
 
+def _global_brightness_message_text() -> str | None:
+    """v1 JSON line for saved zone UI brightness; works with shipping driver firmware (applies ``b`` in RAM)."""
+    global _settings
+    if _settings is None:
+        return None
+    try:
+        b = int(_settings.get("global_brightness", 255))
+    except (TypeError, ValueError):
+        b = 255
+    b = max(0, min(255, b))
+    return json.dumps({"v": "1", "b": b})
+
+
+async def sync_global_brightness_to_driver(ip: str) -> bool:
+    """Push Pi-stored global brightness to one Wi-Fi driver over the outbound WebSocket."""
+    text = _global_brightness_message_text()
+    if not text:
+        return False
+    return await send_json_line_to_ip(ip, text)
+
+
+async def broadcast_global_brightness_to_tcp_drivers() -> None:
+    """Push saved global brightness to every connected Wi-Fi driver."""
+    text = _global_brightness_message_text()
+    if not text:
+        return
+    for ip in list_connected_ips():
+        await send_json_line_to_ip(ip, text)
+
+
 def _register_ws(ip: str, ws) -> None:
     key = normalize_tcp_peer_ip(ip)
     if not key:
@@ -94,6 +124,15 @@ def _register_ws(ip: str, ws) -> None:
         _send_locks[key] = asyncio.Lock()
     _schedule_status_broadcast(key, True)
     print(f"[WS] driver connected {key!r}")
+    try:
+        loop = asyncio.get_running_loop()
+    except RuntimeError:
+        return
+
+    async def _apply_saved_brightness():
+        await sync_global_brightness_to_driver(key)
+
+    loop.create_task(_apply_saved_brightness())
 
 
 def unregister_tcp_writer(peer_ip: str, ws=None) -> str: