TDD: red → green cycle confirmed. New `Code(String)` variant serializes
as `{"code":"rust"}` via serde `rename_all = "lowercase"`. All exhaustive
`match` sites updated (`media_label`, `ingest_one_asset` catch-all →
explicit or-pattern). Design §3.5 enum listing synced. Also fix
`/target` symlink gitignore pattern so integration-test binary lookup
via workspace-relative path works with CARGO_TARGET_DIR redirect.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
altair823
7a6a24ad10