Obter lista de veículos da empresa.

Plain def, NOT async def: the body is a blocking pyodbc query, which on the event loop stalls every other request on this worker (the 2026-07-08 reconnect-herd incident — docs/claude/10-api-patterns.md, and the same note on routes/toc.py::create_invoice). FastAPI runs def handlers in a threadpool. This became load-bearing when the invoice dialog started calling it per keystroke instead of once per open.