docs: move Phase 2.1 cover art to COMPLETED.md

COMPLETED.md

@@ -6,6 +6,22 @@ Newest entries at the top. Group by phase/wave header (mirroring `PLAN.md` / `CM
 
 ---
 
+## Phase 2.1 — Cover art / image vault wired through
+
+**Status:** Fully landed on 2026-06-07 across three waves (Wave 1: API + vault; Wave 2-A: public proxy + TrackCard; Wave 2-B: CMS upload UI), merged to dev.
+
+- **What:** `MediaVaultType.Image` is implemented end-to-end and exercised by tests, but the production surface only registers a `tracks` vault of type `Audio`. `ImagePath` on `TrackEntity` is a free-form URL string today; it should resolve to an entry in an image vault served by `DeepDrftContent`.
+- **Why it matters:** Prerequisite for any album/release/genre view that wants to look like a music site rather than a list of rows. Also closes a free-form-string surface area that will otherwise calcify.
+- **Shape:**
+  - Register a second vault (`images` or `art`, type `Image`) in `Startup.ConfigureDomainServices` and in the CLI.
+  - Add `GET api/image/{entryKey}` (unauthenticated, mirrors track read) and `PUT api/image/{entryKey}` (ApiKey, mirrors track write) on `DeepDrftContent`.
+  - Change `TrackEntity.ImagePath` semantics from "URL" to "image vault entry key" (column rename optional — could remain `image_path` with semantic shift, or could become `image_entry_key` for clarity).
+  - Add an image processor sibling of `AudioProcessor`.
+- **Prerequisite:** None.
+- **Constraint:** This is a small schema-semantics migration. Existing rows have `null` ImagePath in production so there is no data to migrate, but commit before the field has real content to avoid a backfill.
+
+---
+
 ## Embeddable iframe player
 
 **Status:** Feature complete on 2026-06-07 (commit `c83b132 feature: Embed Frame Player`, merged to dev).