feat(resolver): add cross-platform fallback chain

lib/l10n/arb/app_en.arb

@@ -465,6 +465,18 @@
   "@aboutSjdonadoDesc": {
     "description": "Credit description for sjdonado"
   },
+  "aboutUnituneDesc": "Open-source music link resolver by Flaze, used for cross-platform fallback matching.",
+  "@aboutUnituneDesc": {
+    "description": "Credit for the UniTune resolver"
+  },
+  "aboutMusicBrainzDesc": "Open music database maintained by MetaBrainz and its community, used for recording cross-references.",
+  "@aboutMusicBrainzDesc": {
+    "description": "Credit for the MusicBrainz database"
+  },
+  "aboutSquiglyDesc": "Universal music link service by Liam Macmillan, used as a final cross-platform resolver fallback.",
+  "@aboutSquiglyDesc": {
+    "description": "Credit for the Squigly resolver"
+  },
   "aboutAppDescription": "Search music metadata, manage extensions, and organize your library.",
   "@aboutAppDescription": {
     "description": "App description in header card"

lib/screens/settings/about_page.dart

@@ -104,6 +104,29 @@ class AboutPage extends StatelessWidget {
                     githubUsername: 'sjdonado',
                     showDivider: true,
                   ),
+                  _AboutSettingsItem(
+                    icon: Icons.swap_horiz_rounded,
+                    title: 'UniTune',
+                    subtitle: context.l10n.aboutUnituneDesc,
+                    onTap: () => _launchUrl(
+                      'https://github.com/FlazeIGuess/unitune-api',
+                    ),
+                    showDivider: true,
+                  ),
+                  _AboutSettingsItem(
+                    icon: Icons.library_music_outlined,
+                    title: 'MusicBrainz',
+                    subtitle: context.l10n.aboutMusicBrainzDesc,
+                    onTap: () => _launchUrl('https://musicbrainz.org'),
+                    showDivider: true,
+                  ),
+                  _AboutSettingsItem(
+                    icon: Icons.hub_outlined,
+                    title: 'Squigly',
+                    subtitle: context.l10n.aboutSquiglyDesc,
+                    onTap: () => _launchUrl('https://squigly.link'),
+                    showDivider: true,
+                  ),
                   _AboutSettingsItem(
                     icon: Icons.lyrics_outlined,
                     title: 'Paxsenix',