Profile: Media / Work

Carried over from v0.1 (work.md). Media works (audio, image, video) carry a sidecar work.md manifest and/or embedded metadata (ID3 / EXIF / XMP). Same Core fields (model, provider, role, author, human, confidence), packaged as YAML in the manifest. NOTE: v0.1's work.md template declares tap_version: "1.0" while the protocol is 0.x - reconcile to 0.2. Full media profile to be lifted from v0.1 §9 in a later pass.