server: return proper HTTP status codes for error responses (#3707)
Several error paths in the /inference and /load endpoints returned
HTTP 200 with a JSON error body, making it impossible for clients
to distinguish errors from successful responses by status code.
Set 400 for client errors (missing file field, unreadable audio,
missing/invalid model) and 500 for server errors (ffmpeg conversion
failure). The two existing status-code sites (499 for client
disconnect, 500 for processing failure) are unchanged.
overview / pkg / ggml / sources / whisper.cpp / commit