v1.2.9

## What's Changed

### New features
- Added advanced script settings in WebUI:
  - script paragraph count
  - custom script requirements
  - optional full custom system prompt for advanced users
- Added Xiaomi MiMo LLM provider support.
- Added Xiaomi MiMo TTS provider support.
- Improved Ollama default base URL handling for Docker environments.

### Fixes and improvements
- Fixed custom BGM path handling for WebUI and API flows.
- Fixed Windows WebUI launcher robustness.
- Fixed `webui.sh` to bind/open `127.0.0.1` by default instead of opening `0.0.0.0`.
- Fixed string video concat mode handling in downloads.
- Fixed subtitle wrapping for long text.
- Fixed Edge TTS signed-zero rate formatting.
- Added missing Turkish translation keys.
- Fixed README-en ImageMagick code fence.

### Testing
- Added regression coverage for LLM provider behavior, local TTS/video task paths, video concat mode handling, and advanced script prompt settings.
- Verified advanced script settings end-to-end with real script generation, TTS, Pexels material download, subtitle generation, and final video synthesis.