Quality improvements: Unicode chars, Token class, imports, type hints, formatting

fix: re-apply Python 3.10 UTC compatibility (was reverted by formatter)

fix(tests,identity): order-independent event loop + Windows key permissions

fix: 0 test failures; FileService; real RagService; emergency probe; chat return

feat: impl_ref gaps closed — Nemotron/OpenBMB backends, spec refs, extended UI, HOWTO, multi-node E2E

feat: implement all M01-M13, X01-X04 modules + quality gate fixes