From-scratch verification (fresh clone, fresh installs) backing up the P010
completion pass: 256/256 vitest, 28/28 pytest, clean typecheck/build on the
committed tree, pre-existing-only lint noise. Documents that
OPT_QUALITY_BRIDGE_ENABLED ships off and stays off in this PR -- activating
it in production is left as Simon's decision, with a readiness checklist.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
