fix: romaji override delete button (JSON.stringify breaks HTML attr); fix file stem search for en-dash track prefixes

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

src/ui.js

@@ -84,7 +84,7 @@ function _renderRomajiOverrides() {
       <span style="flex:1;font-size:13px;color:var(--text);overflow:hidden;text-overflow:ellipsis;white-space:nowrap">${esc(k)}</span>
       <span style="color:var(--text2);flex-shrink:0">→</span>
       <span style="flex:1.2;font-size:13px;color:var(--text);overflow:hidden;text-overflow:ellipsis;white-space:nowrap">${esc(v)}</span>
-      <button onclick="removeRomajiOverrideUI(${JSON.stringify(k)})" style="background:none;border:none;color:var(--danger);cursor:pointer;font-size:18px;line-height:1;padding:0 2px;flex-shrink:0">×</button>
+      <button onclick="removeRomajiOverrideUI('${esc(k)}')" style="background:none;border:none;color:var(--danger);cursor:pointer;font-size:18px;line-height:1;padding:0 2px;flex-shrink:0">×</button>
     </div>`
   ).join('');
 }