The README had not been touched since the OCR/multi-engine work in August and
described roughly half of what the server does. Add the missing subsystems and
correct the ones that overstated the code:

- Inference engines: the per-model backend matrix (transformers/gguf/ds4/
  colibri/k3/kt/vllm/runpod) and how one is selected.
- RunPod: feature summary plus a full docs/runpod.md — pods vs serverless,
  per-model config keys, cold start, GPU fallback, stuck-boot retry, budgets
  and the ledger, the stale-pod reaper, spillover (with its real scope),
  observability and RunPod-only deployments.
- STT backends, per-model languages/translation, word timestamps, diarization
  and enrolled speaker recognition; embeddings families (BGE-M3 multi-vector,
  GME-Qwen2-VL, GeoCLIP, VPR) and /v1/rerank; the OCR subsystem and its
  schema store; LoRA training.
- API tables for /v1/ocr*, /v1/rerank, /v1/loras*, the audio/speaker routes
  and the two missing pipelines.
- models.json reference incl. multi-config (config_id/alias), the front/engine
  split, optional-subsystem requirements files, and a docs/ index.

Honesty fixes: /v1/pipelines/audio-music-dub is flagged as incomplete (only
the transcription step runs); spillover is documented as serverless-target /
direct-path only.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01R6iugoNeEgt9PkajKrFyq4