Cleanup: fix eslint warnings, button loading state, inspector footer hint

- app.js: replace != with !== (eqeqeq rule) on resolved_24h null check
  and totalActive pagination check
- style.css: extend loading state to all .lt-btn.is-loading (not just
  refresh button), so suppressions form submit shows disabled feedback;
  remove dead .link-collapse-bar rule
- base.html: add inspector page to footer R=REFRESH hint; update
  keyboard shortcut table to include Inspector in refresh shortcut doc

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

templates/base.html

@@ -210,7 +210,7 @@
         <span class="lt-footer-sep">|</span>
         <span class="lt-footer-hint"><span class="lt-footer-key">[ S ]</span> SUPPRESS</span>
         <span class="lt-footer-sep">|</span>
-      {% elif request.endpoint == 'links_page' %}
+      {% elif request.endpoint in ('links_page', 'inspector') %}
         <span class="lt-footer-hint"><span class="lt-footer-key">[ R ]</span> REFRESH</span>
         <span class="lt-footer-sep">|</span>
       {% endif %}
@@ -233,7 +233,7 @@
           <thead><tr><th>Shortcut</th><th>Action</th></tr></thead>
           <tbody>
             <tr><td>Ctrl / &#x2318; + K</td><td>Command palette</td></tr>
-            <tr><td>R</td><td>Refresh data (Dashboard / Link Debug)</td></tr>
+            <tr><td>R</td><td>Refresh data (Dashboard / Link Debug / Inspector)</td></tr>
             <tr><td>S</td><td>Quick-suppress alert (Dashboard)</td></tr>
             <tr><td>*</td><td>Open settings</td></tr>
             <tr><td>?</td><td>Show this help</td></tr>