feat(android): Head-to-Head "Musik-Match" screen (parity with web)

Android CompareScreen mirroring the web feature: partner picker fed by
GET /scrobble/users, then GET /scrobble/compare?with= → a match-score ring
(Canvas arc), per-user totals, mirrored shared-artist bars, shared tracks,
and each side's unique top artists. Rows navigate to artist/album. Reuses the
one PlayLogClient HttpClient (fetchUsers/fetchCompare). Opened from Settings
"🎧 Musik-Match". Parity matrix updated (Android ✅).

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

CHANGELOG.md

@@ -57,7 +57,7 @@ Versioning: two-part `MAJOR.MINOR` — each release bumps the minor (features an
 | Timestamped play-log (own scrobble)  | ✅        | ✅      |
 | Listening statistics view            | ✅        | ✅      |
 | Stats cover art (artist/album)       | ✅        | ✅      |
-| Musik-Match (Head-to-Head)           | ✅        | 🔜      |
+| Musik-Match (Head-to-Head)           | ✅        | ✅      |
 | Yearly Wrapped                       | 🔜        | 🔜      |
 | Romaji / Japanese sort           | ✅        | ❌      |
 | Settings (Navidrome, ABS, etc.)  | ✅        | ✅      |