fix(ci): unblock the format gate — ruff 0.16 formats Markdown code blocks

[r-uben]

Summary

main is currently red on the repo-wide format check, with no code change
required to trigger it. Every open PR inherits the failure.

Root cause

CI runs uv run ruff format --check . (.github/workflows/ci.yml:31).

• pyproject.toml declares ruff>=0.8.0 (unpinned) and CI does not pass
  --frozen, so uv run resolves ruff latest = 0.16.0, not the 0.15.17
  pinned in uv.lock.
• Ruff 0.16 formats Python code blocks inside Markdown by default. 0.15.17
  refuses: Markdown formatting is experimental, enable preview mode.
• Result: CI checks 220 files (130 .py + 90 .md) where a local
  ~/venvs/socr/bin/ruff format --check . checks only 130 and reports clean.

So a ruff release turned an untouched, previously-passing file into a build
failure, and the failure is not locally reproducible with the repo's own
pinned toolchain.

This PR

Realigns two trailing comments in docs/MODELS.md. Whitespace only, no content
change:

-AUTO_ENGINE_ORDER = [QWEN, GEMINI, MARKER, GLM, NOUGAT]   # DeepSeek + Mistral dropped
+AUTO_ENGINE_ORDER = [QWEN, GEMINI, MARKER, GLM, NOUGAT]  # DeepSeek + Mistral dropped

Unblocks #99, #100, #101.

What this does NOT fix

The drift itself. The next ruff release can red main the same way. Options,
none taken here because it is a repo-policy call:

1. Pin ruff exactly in pyproject.toml (matching uv.lock), so the gate is
   reproducible locally — my preference, since CLAUDE.md calls lint a blocking
   gate and a blocking gate that can't be reproduced locally is a trap.
2. Run CI with uv run --frozen, honouring uv.lock.
3. Accept markdown formatting deliberately and add it to the documented local
   command in CLAUDE.md, so contributors run the same check CI does.

Worth noting for (3): CLAUDE.md currently documents
~/venvs/socr/bin/ruff format --check <files> as the gate. That venv has ruff
0.15.15 and will never reproduce CI's markdown check.

Test plan — observed results

• uvx ruff@latest format --check . → before: 2 files would be reformatted, 218 files already formatted; after this commit plus the bake-off note fix: clean.
• uvx ruff@latest format --check docs/MODELS.md → 1 file already formatted
• ~/venvs/socr/bin/pytest tests/ -q → 1249 passed, 1 xfailed (unchanged;
  this touches no Python)