* feat(webui): add preset save/load/manage support

* fix(webui): fix preset initialization and loading issues

* feat(cli/webui): expose use_accel and use_torch_compile options

- Add --accel/--torch-compile flags to CLI v2 synth and batch commands
- Add use_accel/use_torch_compile to persisted config keys
- Pass both options through to IndexTTS2 in CLI and WebUI
- Update relevant CLI tests for new runtime options

* feat(webui): add UI checkboxes for use_accel and use_torch_compile in advanced settings

- Add two checkboxes in the advanced settings accordion
- Default values follow the --accel / --torch_compile CLI flags
- Rebuild the IndexTTS2 engine when checkbox values differ from current instance

* feat: expose accel/torch_compile as startup args only; add optional extras

* docs: remove Windows acceleration note from README

* test(cli): mock flash_attn/triton imports in no-GPU CLI tests

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Co-authored-by: Jennie <wangyihui02@bilibili.com>