refactor: modularize API routes into separate files and clean up dependencies

decnet/web/router/fleet/api_get_deckies.py

@@ -0,0 +1,12 @@
+from typing import Any
+
+from fastapi import APIRouter, Depends
+
+from decnet.web.dependencies import get_current_user, repo
+
+router = APIRouter()
+
+
+@router.get("/deckies", tags=["Fleet Management"])
+async def get_deckies(current_user: str = Depends(get_current_user)) -> list[dict[str, Any]]:
+    return await repo.get_deckies()