v0.3.1

First tagged build of the 0.3 line off `main` — it ships the accumulated
`[0.3.0]` work below plus the fixes here. (The `[0.3.0]` milestone heading is
kept for the qualitative "actually useful" release.)

### Fixed
- **Voice-clone / export download crashed in the Docker & browser build** with
  `TypeError: Cannot read properties of undefined (reading 'invoke')`. The
  export button called the Tauri save dialog unconditionally; outside the
  desktop shell it now falls back to a standard browser download of the file
  served at `/audio/<path>`. (#256)
- **Docker container showed no version** (a dash) in Settings → About, and the
  desktop-only update-channel toggle appeared in the web build. The running
  version is now read from the backend (`/system/info` `app_version`, `/health`
  `version`); the updater UI is hidden outside Tauri. Also corrected the
  version-check command in the Docker docs (`omnivoice`, not
  `omnivoice-studio`). (#249)
- **Transcription failures were masked** by a generic "Transcribe stream
  dropped" message. The transcribe SSE stream now surfaces the real, sanitized
  cause (with an actionable hint) instead of silently dropping when model load
  or VRAM offload fails. (#255)
### Windows x64 artifacts

```
1f7fb7064f5813330705baa6e0b7fb110fb8257838594e81d51c7935f13ec959 *OmniVoice Studio_0.3.1_x64_en-US.msi
1aa38c6bd0147fadba3a1c083a581ced07ad857eef30ced1e262061c9cf8351a *OmniVoice Studio_0.3.1_x64_en-US.msi.sig
```