Location: say why it failed, retry once, show permission status

The ⌖ button reported 'Location access denied' for every failure, including timeouts and
no-GPS-fix errors that have nothing to do with permission.

- Specific messages for denied / no fix / timeout, with the exact iPhone steps (Safari tab vs
  installed web app) and the error code for diagnosis
- One patient high-accuracy retry for slow or cold GPS fixes (a real denial is not retried)
- Live permission status line under the search row (allowed / not asked / blocked)
- Mentions Safari content blockers as a possible cause

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

app/public/index.html

@@ -449,6 +449,7 @@
           <button id="units-btn" title="Toggle units">US</button>
         </div>
         <ul id="suggestions" class="suggestions hidden"></ul>
+        <p id="geo-status" class="geo-status hidden" role="status"></p>
         <p id="error-msg" class="error hidden"></p>
       </div>