fix: circular import causing navigate undefined; unified importer input

- Remove top-level ui.js import from soundcloud.js (broke views.js→soundcloud.js→ui.js→views.js cycle)
- Use window.executeSpotifyDownload() instead to avoid the circular dep
- Merge Spotify + SoundCloud into one unified URL input that auto-detects
  the service and colors the badge/button accordingly
- resolveImporterLink() routes to the correct handler based on URL

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.js

@@ -18,7 +18,8 @@ import {
   loadAlbums, loadStarred, loadRandom, filterStarred, filterPlaylist,
   plReorderEnter, plReorderSave, plReorderCancel, toggleAllGenres,
 } from './views.js';
-import { loadSpotifyImporter, resolveSpotifyLink, clearSpotifyPreview, spotifyDlAll } from './spotify.js';
+import { loadSpotifyImporter, resolveSpotifyLink, clearSpotifyPreview, spotifyDlAll,
+         onImporterInput, resolveImporterLink } from './spotify.js';
 import { loadSoundCloudImporter, resolveSoundCloudLink, clearSoundCloudPreview, scDlAll } from './soundcloud.js';
 import {
   absInitFromStorage, absOpenSettings, absConnectSettings, absSetLibrary, absDisconnect, absVerifyApiKey,
@@ -308,6 +309,7 @@ Object.assign(window, {
   loadAlbums, loadStarred, loadRandom, filterStarred, filterPlaylist,
   plReorderEnter, plReorderSave, plReorderCancel, toggleAllGenres,
   loadSpotifyImporter, resolveSpotifyLink, clearSpotifyPreview, spotifyDlAll,
+  onImporterInput, resolveImporterLink,
   loadSoundCloudImporter, resolveSoundCloudLink, clearSoundCloudPreview, scDlAll, scDlSingle, scDlTrack,
   executeSpotifyDownload,
   openPlModal, closePlModal, addSongsToPlaylist, createAndAddPlaylist, createPlaylistPrompt,