ocr: fix PaddleOCR 3.x API + pin surya-ocr to classic local-torch 0.6.4

- PaddleOCR 3.7 dropped use_gpu/use_angle_cls/show_log and raises ValueError for
  unknown ctor args; worker now tries 3.x (device=) then 2.x kwargs and prefers
  .predict() over .ocr(). Verified on a real scanned IT legal page.
- surya-ocr >=~0.15 ('Surya2') rearchitected to a VLM needing an external
  vLLM-in-Docker or llama-server backend (SpawnError in an isolated venv). Pin to
  0.6.4 which runs det+recognition locally on torch, matching the worker's API.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mw2KQiswmD69T45fTfjKwW