fix: add _profile_arg tests + move STT language to config.yaml

- Add 7 unit tests for _profile_arg: default home, named profile,
  hash path, nested path, invalid name, systemd integration, launchd integration
- Add stt.local.language to config.yaml (empty = auto-detect)
- Both STT code paths now read config.yaml first, env var fallback,
  then default (auto-detect for faster-whisper, 'en' for CLI command)
- HERMES_LOCAL_STT_LANGUAGE env var still works as backward-compat fallback

hermes_cli/config.py

@@ -416,6 +416,7 @@ DEFAULT_CONFIG = {
         "provider": "local",  # "local" (free, faster-whisper) | "groq" | "openai" (Whisper API)
         "local": {
             "model": "base",  # tiny, base, small, medium, large-v3
+            "language": "",  # auto-detect by default; set to "en", "es", "fr", etc. to force
         },
         "openai": {
             "model": "whisper-1",  # whisper-1, gpt-4o-mini-transcribe, gpt-4o-transcribe