Coverage 83.6 to 87.36% lines, 81.63 to 84.14% branches. Mutation testing across five packages: image-engine 85, media-engine 92, doc-engine 87, shared+enterprise 86, apps/api security and jobs slice. Runs all five lanes weekly. Fixes the silently-broken mutation CI (babel pin), a redact-pdf envelope-shape test bug, an untested enterprise license valid-signature path, and an audit test that only exercised a hand-copied reproduction. Test and config only, no product code changes beyond the babel pin and one test-only oidc export. Full suite: 16,712 pass, 0 fail.
Centralizes the sharp format key type into a single `SharpFormat` alias derived from `toFormat()`'s signature (exported from @snapotter/image-engine, imported by the API consumers), replacing the duplicated `keyof FormatEnum` definitions. Adds convert/compress format round-trip tests covering webp/avif/png/jpeg. Part of #325.
