Add auth.disabled_providers config to skip auth providers

Reads disabled_providers list from instance.yaml auth section.
Listed providers are skipped during auto-discovery.

auth/__init__.py

@@ -68,7 +68,11 @@ def discover_providers() -> list[AuthProvider]:
     Each provider module must export a `provider` instance of AuthProvider.
     Providers are sorted by login button order.
     Only available providers (is_available() == True) are returned.
+    Providers listed in Config.AUTH_DISABLED_PROVIDERS are skipped.
     """
+    from webapp.config import Config
+
+    disabled = [name.lower() for name in (Config.AUTH_DISABLED_PROVIDERS or [])]
     providers = []
     auth_dir = Path(__file__).parent
 
@@ -83,7 +87,11 @@ def discover_providers() -> list[AuthProvider]:
             mod = importlib.import_module(f"auth.{subdir.name}.provider")
             provider_instance = getattr(mod, "provider", None)
             if provider_instance and isinstance(provider_instance, AuthProvider):
-                if provider_instance.is_available():
+                if provider_instance.get_name().lower() in disabled:
+                    logger.info(
+                        f"Auth provider disabled by config: {provider_instance.get_name()}"
+                    )
+                elif provider_instance.is_available():
                     providers.append(provider_instance)
                     logger.info(f"Auth provider loaded: {provider_instance.get_name()}")
                 else:

webapp/config.py

@@ -112,6 +112,9 @@ class Config:
     THEME_PRIMARY_DARK = _get(_instance, "theme", "primary_dark", default="")
     THEME_PRIMARY_LIGHT = _get(_instance, "theme", "primary_light", default="")
 
+    # Auth providers to disable (list of provider names, e.g., ["email", "password"])
+    AUTH_DISABLED_PROVIDERS = _get(_instance, "auth", "disabled_providers", default=[])
+
     # Telegram bot
     TELEGRAM_BOT_USERNAME = _get(_instance, "telegram", "bot_username", default="")