feat(misc): support seasonal backgrounds

app/router/misc.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime
+
+from app.config import settings
+
+from .api_router import router
+
+from pydantic import BaseModel
+
+
+class Background(BaseModel):
+    url: str
+
+
+class BackgroundsResp(BaseModel):
+    ends_at: datetime = datetime(year=9999, month=12, day=31, tzinfo=UTC)
+    backgrounds: list[Background]
+
+
+@router.get("/seasonal-backgrounds", response_model=BackgroundsResp)
+async def get_seasonal_backgrounds():
+    return BackgroundsResp(
+        backgrounds=[Background(url=url) for url in settings.seasonal_backgrounds]
+    )