feat: tracklist column reset, device sync cross-platform template fix, filename template builder, privacy policy

- Add "Reset to defaults" button to column picker in AlbumTrackList, PlaylistDetail, Favorites (all 8 locales)
- Fix device sync cross-OS status detection: store filenameTemplate in manifest, use it for path computation on import
- Redesign filename template UI: preset buttons (Standard/Multi-Disc/Alt. Folder), clickable token chips ({artist}, {album}, etc.), clear button
- Fix suggestions section in PlaylistDetail missing album column rendering
- Add PRIVACY.md documenting all third-party integrations (Last.fm, LRCLIB, Apple Music, Discord); link from README

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

src/locales/en.ts

@@ -155,6 +155,7 @@ export const enTranslation = {
     trackDuration: 'Duration',
     trackTotal: 'Total',
     columns: 'Columns',
+    resetColumns: 'Reset to defaults',
     notFound: 'Album not found.',
     bioModal: 'Artist Biography',
     bioClose: 'Close',
@@ -1101,6 +1102,10 @@ export const enTranslation = {
     actionDelete: 'Delete from Device',
     actionApplyAll: 'Apply All Changes',
     templatePreview: 'Preview',
+    templatePresetStandard: 'Standard',
+    templatePresetMultiDisc: 'Multi-Disc',
+    templatePresetAltFolder: 'Alt. Folder',
+    tokenSlashHint: '/ = folder separator',
     cancel: 'Cancel',
     noTargetDir: 'Please choose a target folder first.',
     noSources: 'Please select at least one source.',