docs(audit): Phase 1 — reconcile stale checkboxes + fix roadmap drift

Tick items whose root cause already landed, and fix two doc-drift items:

- L82: align ROADMAP-PINCHFLAT Phase F Source/MediaItem sketch to the shipped
  shared/ipc.ts shape (videoId/itemCount/watched/feedUrl + required
  url/playlistTitle/playlistIndex).
- L89: note H8's afterAllArtifactBuild checksum hook fixes release-artifact
  consistency going forward; stale dist artifacts handled by L84.
- Tick the wire-or-remove trio (M5/M6/UX1 — all wired in the DownloadBar
  Advanced panel) and MAX_ENQUEUE_BATCH (M33 fixed the false comment).
- Tick UX ref-duplicates resolved by their roots (UX10=H5, UX13=M22, UX14=L76,
  UX25=L78), the (ref) a11y line (UI33/UI30/UI28/UI29 all done), and the
  (OK)/(non-goal) Windows-conventions line.

Docs only; no code touched. 149 -> 137 open audit items.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ROADMAP-PINCHFLAT.md

@@ -109,19 +109,26 @@ yet. This is the prerequisite for every later phase.
         channel?: string
         addedAt: number
         lastIndexedAt?: number
+        itemCount: number      // cached MediaItem count for list display
+        watched?: boolean      // included in scheduled / startup sync (Phase J)
+        feedUrl?: string       // YouTube RSS feed for cheap "anything new?" checks
       }
       interface MediaItem {
-        id: string            // yt-dlp video id — the dedup key
+        id: string             // globally unique, `${sourceId}:${videoId}`
         sourceId: string
+        videoId: string        // yt-dlp video id — the dedup key within a source
         title: string
-        playlistTitle?: string // for the folder path; 'Uploads' fallback
-        playlistIndex?: number // 1-based, for NNN numbering
+        url: string
+        playlistTitle: string  // for the folder path; 'Uploads' fallback
+        playlistIndex: number  // 1-based, for NNN numbering
         durationLabel?: string
         downloaded: boolean
         downloadedAt?: number
         filePath?: string
       }
       ```
+      *(This block reflects the shipped `src/shared/ipc.ts` shape; the original sketch
+      predated the `videoId`/`itemCount`/`watched`/`feedUrl` fields.)*
 - [x] **Dedup on index.** A video appearing in multiple playlists collapses to one `MediaItem`
       (keyed by video id); first playlist seen wins the folder assignment (surface this choice
       in the UI so the user can reassign). The "Uploads" synthetic playlist catches anything in