docs: add FunASR SenseVoice STT setup

[LauraGPT]

Summary

• add a tested FunASR/SenseVoice example to the existing OpenAI-compatible STT documentation
• document environment setup, server startup, endpoint verification, LibreChat YAML, and host/container URL choices
• clarify that the local server does not require an API key by default
• fix the adjacent OpenAI-compatible example's mis-indented closing code fence

Why

The speech settings page already states that LibreChat supports OpenAI-compatible STT services, but it only shows a generic Whisper example. This addition gives users a reproducible self-hosted option for multilingual speech recognition, including Mandarin, Cantonese, English, Japanese, and Korean, without adding a bespoke provider to LibreChat.

Validation

Validated after rebasing signed commit 4e726cbf645c329e74cbbbe1af14a4fa63c31adc onto main at 123cfd4df61c4894d8a779264325ab2488dc32a8:

• FunASR 1.3.27 CPU server health check: HTTP 200
• LibreChat-shaped multipart request (file, model=sensevoice, language=zh): HTTP 200 in 0.574s and returned {"text":"欢迎大家来体验达摩院推出的语音识别模型"}
• pnpm install --frozen-lockfile
• pnpm lint
• pnpm test (21 files, 184 tests)
• pnpm typecheck
• pnpm exec prettier --check content/docs/configuration/stt_tts.mdx
• pnpm build (2,877 static pages generated)
• production runtime check at /en/docs/configuration/stt_tts for the FunASR heading, server command, OpenAI-compatible endpoint, model value, and host/container URL
• git diff --check

The Vercel status requires authorization from a member of the LibreChat Vercel team; the production build and runtime route pass locally at the exact PR head.

[vercel]

@LauraGPT is attempting to deploy a commit to the LibreChat's projects Team on Vercel.

A member of the Team first needs to authorize it.

[LauraGPT]

@berry-13 This FunASR/SenseVoice STT docs integration is now rebased onto current main at signed head 4e726cbf. Exact-head validation passes lint, 184 tests, typecheck, Prettier, the full 2,877-page production build, the rendered docs route, and a real FunASR 1.3.27 CPU transcription. The sole red status is Vercel team authorization, not a build failure. Could you review it when convenient?