feat: add video OCR/ASR, DOCX/PDF export, input block and risk config updates

- Video pipeline: video file OCR via VLM plus audio track ASR, integrated
  into job_handlers with progress emit per phase. New media_utils.py for
  audio extraction from video files.
- Document export: richExport.js replaces inline docx builder; DOCX and PDF
  export buttons are now enabled in MilkdownEditor. File size limit raised to
  100 MB.
- Input block: new InputBlockCrepe.vue component with inputBlockPlugin.ts
  and inputBlock.js for custom user-input nodes in the editor.
- Risk config: added Vite dev server ports (5173) to CORS allowlist and
  increased OCR max input from 10 MB to 100 MB.
- TTS/ASR refactor: simplified tts_asr.py model loading and warmup logic.
- Test coverage: updated tests for llm, main endpoints, pro completions and
  web search modules.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/requirements.docker.txt

@@ -8,3 +8,10 @@ python-multipart>=0.0.9
 python-dotenv>=1.0.0
 markitdown>=0.1.1
 geoip2>=4.8.0
+numpy>=1.26.0
+torch>=2.2.0
+soundfile>=0.12.1
+scipy>=1.13.0
+qwen-tts
+modelscope>=1.18.0
+faster-whisper>=1.1.0