Internal-only epic (gates, tests, compiler strictness); no user-facing change, so
the release note is chores-only. Bundles: the siftlode check/publish gate
(tsc/eslint/prettier/knip/vitest/pytest) with a hard pre-publish gate + e2e
freshness guard, ESLint flat config + one-time Prettier pass, the backend pytest
harness (isolated test image), frontend vitest growth, the e2e scroll-restore fix,
and noUncheckedIndexedAccess (+ the zero-fallout compiler flags).