Harden account import/continuous behavior and finish multi-account UI polish

webui/index.html

@@ -81,6 +81,10 @@
             <input id="add-account-api-hash" name="api_hash" placeholder="API Hash" />
             <button class="button primary" type="submit">Add Account</button>
           </form>
+          <label class="import-account-row">
+            <span class="muted small">Import account settings JSON</span>
+            <input id="import-account-file" type="file" accept="application/json,.json" />
+          </label>
         </section>
 
         <!-- ── Account Auth ── (shown per account selected in UI) -->
@@ -165,6 +169,11 @@
               <div class="section-title">Forwarding rules</div>
               <div class="stat-value forwarding-count">0</div>
             </div>
+            <div class="panel stat-panel">
+              <div class="section-title">Account health</div>
+              <div class="stat-value stat-compact account-health-label">-</div>
+              <div class="muted small account-health-detail"></div>
+            </div>
           </section>
 
           <section class="panel">
@@ -300,6 +309,7 @@
         </div>
         <div class="account-list-actions">
           <button class="button button-small account-select-btn">Select</button>
+          <button class="button button-small account-export-btn">Export</button>
           <button class="button button-small danger account-remove-btn">Remove</button>
         </div>
       </div>