Add backup-first duplicate repair

serato_doctor/webui/index.html

@@ -23,7 +23,7 @@
       </nav>
       <div class="safety-card">
         <span class="safety-icon">✓</span>
-        <div><strong>Read-only mode</strong><p>Your library will not be modified.</p></div>
+        <div><strong>Protected mode</strong><p>Analysis is read-only. Repairs require a preview and backup.</p></div>
       </div>
       <div class="sidebar-foot">Local interface · v0.1</div>
     </aside>
@@ -88,6 +88,23 @@
           <p id="drilldown-summary">Click a metric above to see example files and saved paths behind that number.</p>
           <div id="drilldown-list" class="detail-list"></div>
         </div>
+
+        <div id="duplicate-repair" class="repair-panel panel" hidden>
+          <div class="section-heading"><div><p class="eyebrow">Backup-first cleanup</p><h2>Safely consolidate duplicates</h2></div><span class="repair-tag">Preview required</span></div>
+          <p>Choose the real file to keep. Every other path will be backed up and replaced with a shortcut to it, so existing Serato crates remain mapped. Serato’s database V2 is never edited.</p>
+          <div id="repair-choice" class="repair-choice"></div>
+          <div class="backup-options">
+            <label>Backups to keep <input id="backup-limit" type="number" min="1" value="10"></label>
+            <label class="check-label"><input id="keep-all-backups" type="checkbox"> Keep every backup</label>
+          </div>
+          <div id="repair-preview" class="repair-preview" hidden></div>
+          <div class="repair-actions">
+            <button id="preview-repair" type="button">Preview changes</button>
+            <button id="apply-repair" class="danger-action" type="button" disabled>Apply backed-up cleanup</button>
+            <button id="restore-repair" type="button" hidden>Restore this backup</button>
+          </div>
+          <div id="repair-message" class="repair-message" role="status"></div>
+        </div>
       </section>
     </main>
   </div>