fix(modals): add missing btn base class and update acknowledgments

- Fix modal footer buttons missing 'btn' base class in:
  - PlaylistModal (New/Edit playlist, Add to playlist)
  - PlaylistImportModal (Import playlist)
  - FolderSettingsModal (Library folder settings)
  - Sidebar (New folder inline modal)
- Remove incorrect QobuzLegalNotice from PlaylistImportModal
- Add MusicBrainz and lyrics providers to AboutModal acknowledgments:
  - MusicBrainz (music metadata)
  - LRCLIB (synced lyrics)
  - lyrics.ovh (lyrics API)

src/lib/components/AboutModal.svelte

@@ -123,9 +123,18 @@
             <div class="attribution">
               <strong>Lucide</strong> — Icon library (ISC)
             </div>
+            <div class="attribution">
+              <strong>MusicBrainz</strong> — Music metadata database
+            </div>
             <div class="attribution">
               <strong>Song.link/Odesli</strong> — Music link aggregation API
             </div>
+            <div class="attribution">
+              <strong>LRCLIB</strong> — Synced lyrics provider
+            </div>
+            <div class="attribution">
+              <strong>lyrics.ovh</strong> — Lyrics API
+            </div>
           </div>
         </div>
 

src/lib/components/FolderSettingsModal.svelte

@@ -365,10 +365,10 @@
           {scanning ? $t('library.scanning') : $t('library.scanThisFolder')}
         </button>
         <div class="footer-spacer"></div>
-        <button class="btn-secondary" onclick={onClose} disabled={loading}>
+        <button class="btn btn-secondary" onclick={onClose} disabled={loading}>
           {$t('actions.cancel')}
         </button>
-        <button class="btn-primary" onclick={handleSave} disabled={loading}>
+        <button class="btn btn-primary" onclick={handleSave} disabled={loading}>
           {loading ? $t('actions.saving') : $t('actions.save')}
         </button>
       </div>

src/lib/components/PlaylistImportModal.svelte

@@ -3,8 +3,6 @@
   import { X, CloudOff } from 'lucide-svelte';
   import { showToast } from '$lib/stores/toastStore';
   import { t } from '$lib/i18n';
-  import QobuzLegalNotice from '$lib/components/QobuzLegalNotice.svelte';
-  import { qobuzTosAccepted } from '$lib/stores/qobuzLegalStore';
   import {
     subscribe as subscribeOffline,
     isOffline as checkIsOffline
@@ -70,7 +68,7 @@
 
   const detectedProvider = $derived(detectProvider(url));
   const activeProvider = $derived(lockedProvider ?? detectedProvider);
-  const isValid = $derived(!!detectedProvider && !isOffline && $qobuzTosAccepted);
+  const isValid = $derived(!!detectedProvider && !isOffline);
 
   $effect(() => {
     if (isOpen) {
@@ -213,8 +211,6 @@
       </div>
 
       <div class="modal-body">
-        <QobuzLegalNotice checkboxDisabled={loading} />
-
         {#if isOffline}
           <div class="offline-warning" role="alert" aria-live="polite">
             <CloudOff size={16} aria-hidden="true" />
@@ -280,8 +276,8 @@
       </div>
 
       <div class="modal-footer">
-        <button class="btn-secondary" onclick={onClose} disabled={loading}>Close</button>
-        <button class="btn-primary" onclick={handleImport} disabled={!isValid || loading || importCompleted}>
+        <button class="btn btn-secondary" onclick={onClose} disabled={loading}>Close</button>
+        <button class="btn btn-primary" onclick={handleImport} disabled={!isValid || loading || importCompleted}>
           {#if loading}
             Importing...
           {:else}

src/lib/components/PlaylistModal.svelte

@@ -577,10 +577,10 @@
           </div>
         {/if}
         <div class="footer-right">
-          <button class="btn-secondary" onclick={onClose} disabled={loading}>
+          <button class="btn btn-secondary" onclick={onClose} disabled={loading}>
             Cancel
           </button>
-          <button class="btn-primary" onclick={handleSubmit} disabled={loading}>
+          <button class="btn btn-primary" onclick={handleSubmit} disabled={loading}>
             {#if loading}
               Saving...
             {:else if mode === 'create'}

src/lib/components/Sidebar.svelte

@@ -1140,11 +1140,11 @@
         />
       </div>
       <div class="modal-actions">
-        <button class="btn-secondary" onclick={cancelCreateFolder}>
+        <button class="btn btn-secondary" onclick={cancelCreateFolder}>
           {$t('actions.cancel')}
         </button>
         <button
-          class="btn-primary"
+          class="btn btn-primary"
           onclick={handleCreateFolder}
           disabled={!newFolderName.trim()}
         >