feat: add remote device settings portal and Pi hot reload

- add /settings/device portal page and portal device-config GET endpoint
- add portal navigation and client-side device settings editor UI
- hot-reload Account/Car display config after local saves and server syncs
- document portal workflow and Phase 25.5b completion
- add runtime reload tests for account, car, and sync callback

Co-authored-by: Copilot <[email protected]>

modules/app_device_sync.py

@@ -17,6 +17,7 @@ from . import app_network, app_sql
 _SYNC_THREAD = None
 _SYNC_STOP = False
 _SYNC_CONFIG_VERSION = 0  # Track last-synced version to detect changes
+_RELOAD_CALLBACK = None
 
 
 def _has_internet():
@@ -44,6 +45,12 @@ def start_sync():
     _SYNC_THREAD.start()
 
 
+def register_reload_callback(callback):
+    """Register a callback invoked after synced config is written locally."""
+    global _RELOAD_CALLBACK
+    _RELOAD_CALLBACK = callback
+
+
 def stop_sync():
     """Stop background device config sync thread."""
     global _SYNC_STOP
@@ -112,10 +119,8 @@ def _store_synced_config(config):
 
 def _on_config_changed():
     """Called when config changes and needs to be reloaded by app."""
-    # This is a signal for future hot-reload implementation
-    # For now, config is automatically read from database on each request
-    # A full reload would require restarting the app or using a signal handler
-    pass
+    if _RELOAD_CALLBACK is not None:
+        _RELOAD_CALLBACK()
 
 
 def is_sync_enabled():