qpdf expands argument files before parsing options, so a bare positional password
beginning with @ was resolved as a path and the file's contents became the
encryption key: exit 0, and the user's own password no longer opened the PDF.
Drive the encrypt through a job-JSON file so neither password reaches argv. The
=-joined flag form needs qpdf 11.7+, and the released image carries 11.3.0 which
rejects it; job JSON works on both (verified 11.3.0 and 12.1.0, R = 6 each).
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.
