Increase minimum check interval to 60 seconds

PokemonCenter's Imperva bot protection bans IPs that hit
too frequently. 10 seconds was too aggressive.

- New minimum: 60 seconds
- New default: 90 seconds
- Updated popup UI to reflect safer limits

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chrome-extension/popup.html

@@ -215,8 +215,8 @@
   <div class="row">
     <div>
       <label>Check Interval (seconds)</label>
-      <input type="number" id="interval" min="10" max="300" value="15">
-      <small>Min 10 sec. Recommended: 15-30 sec</small>
+      <input type="number" id="interval" min="60" max="300" value="90">
+      <small>Min 60 sec to avoid bans. Recommended: 90 sec</small>
     </div>
   </div>