fix: use proper i18n keys in TrackReplacementModal

Added playlist-specific keys for search button, cancel, loading,
and preview instead of generic common.* keys that didn't exist.

src/lib/components/TrackReplacementModal.svelte

@@ -151,7 +151,7 @@
             {#if loading}
               <Loader2 size={16} class="spinner" />
             {:else}
-              {$t('search.search')}
+              {$t('playlist.searchButton')}
             {/if}
           </button>
         </div>
@@ -161,7 +161,7 @@
         {#if loading}
           <div class="loading-state">
             <Loader2 size={24} class="spinner" />
-            <span>{$t('common.loading')}</span>
+            <span>{$t('playlist.loading')}</span>
           </div>
         {:else if searched && results.length === 0}
           <div class="empty-state">
@@ -201,7 +201,7 @@
                   <button
                     class="preview-btn"
                     onclick={(e) => handlePreview(e, track)}
-                    title={$t('common.preview')}
+                    title={$t('playlist.preview')}
                   >
                     <Play size={14} fill="currentColor" />
                   </button>
@@ -224,7 +224,7 @@
 
       <div class="modal-footer">
         <button class="cancel-btn" onclick={onClose}>
-          {$t('common.cancel')}
+          {$t('playlist.cancel')}
         </button>
         <button
           class="confirm-btn"

src/lib/i18n/locales/en.json

@@ -203,7 +203,11 @@
     "replaceTrack": "Replace Track",
     "lookForAvailableVersion": "Look for available version",
     "trackReplaced": "Track replaced successfully",
-    "trackReplaceFailed": "Failed to replace track"
+    "trackReplaceFailed": "Failed to replace track",
+    "searchButton": "Search",
+    "cancel": "Cancel",
+    "loading": "Searching...",
+    "preview": "Preview"
   },
   "sort": {
     "nameAZ": "Name (A-Z)",

src/lib/i18n/locales/es.json

@@ -203,7 +203,11 @@
     "replaceTrack": "Reemplazar Pista",
     "lookForAvailableVersion": "Buscar versión disponible",
     "trackReplaced": "Pista reemplazada exitosamente",
-    "trackReplaceFailed": "Error al reemplazar pista"
+    "trackReplaceFailed": "Error al reemplazar pista",
+    "searchButton": "Buscar",
+    "cancel": "Cancelar",
+    "loading": "Buscando...",
+    "preview": "Vista previa"
   },
   "sort": {
     "nameAZ": "Nombre (A-Z)",