feat: implement raycast backend

src/beaver_gateway/settings.py

@@ -29,3 +29,18 @@ class Settings(BaseSettings):
 
     raycast_bearer: str | None = None
     raycast_config_path: Path = Path("/config/raycast.json")
+    raycast_device_id: str | None = None
+    """64-hex-char stable per-install id. Required when any ``RaycastAgent``
+    is configured — generate once via ``secrets.token_hex(32)`` and keep
+    in ``.env`` so Raycast doesn't see every restart as a new device."""
+
+    raycast_locale: str = "en-US"
+    """``Accept-Language`` header sent by the shared ``raycast_api.Client``
+    and the default locale used to render auto ``UserPreferences``. One
+    value per gateway since we open one Client total."""
+
+    bootstrap_tokens: str = ""
+    """Phase 1.3 seed: ``name1:value1,name2:value2``. Empty = no auth wired yet.
+
+    Phase 4 moves tokens into the DB. Until then this is the only source.
+    """