feat(web): Enter in the importer field starts the import

Pressing Enter in the importer link input now triggers resolveImporterLink()
(same as the Importieren button). Bump SW cache to ns-v45.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

index.html

@@ -401,7 +401,7 @@
           <div style="display:flex;gap:8px">
             <div class="search-box" style="background:var(--surface);border-color:var(--border2);flex:1">
               <div id="importer-badge" style="font-size:10px;font-weight:700;padding:2px 7px;border-radius:10px;background:var(--surface2);color:var(--text3);white-space:nowrap;flex-shrink:0">URL</div>
-              <input id="importer-link-input" type="url" placeholder="Spotify, SoundCloud oder YouTube Link einfügen…" style="font-size:14px" oninput="onImporterInput(this.value)">
+              <input id="importer-link-input" type="url" placeholder="Spotify, SoundCloud oder YouTube Link einfügen…" style="font-size:14px" oninput="onImporterInput(this.value)" onkeydown="if(event.key==='Enter'){event.preventDefault();resolveImporterLink()}">
             </div>
             <button id="importer-btn" class="btn-outline" style="padding:0 16px;font-size:13px;font-weight:700;white-space:nowrap;flex-shrink:0" onclick="resolveImporterLink()">Importieren</button>
           </div>