feat(ui): add setting to keep the action bar visible while scrolling (#1095)

Adds a 'Keep Action Bar Visible' toggle (default off) under
Settings > Interface > Layout Settings. When enabled, the controls bar
(Refresh, Download, etc.) and the breadcrumb nav are wrapped in a shared
sticky container (.sticky-topbar) so both stay pinned as one unit; when
disabled, the wrapper is display: contents and the original behavior
(only the breadcrumb stays visible) is preserved.

static/js/managers/SettingsManager.js

@@ -1047,6 +1047,12 @@ export class SettingsManager {
             groupByModelCheckbox.checked = !!state.global.settings.group_by_model;
         }
 
+        // Set sticky controls
+        const stickyControlsCheckbox = document.getElementById('stickyControls');
+        if (stickyControlsCheckbox) {
+            stickyControlsCheckbox.checked = !!state.global.settings.sticky_controls;
+        }
+
         // Set model name display setting
         const modelNameDisplaySelect = document.getElementById('modelNameDisplay');
         if (modelNameDisplaySelect) {
@@ -3396,6 +3402,10 @@ export class SettingsManager {
         const groupByModel = !!state.global.settings.group_by_model;
         document.body.classList.toggle('group-by-model', groupByModel);
 
+        // Apply sticky controls mode (keeps the action bar visible while scrolling)
+        const stickyControls = !!state.global.settings.sticky_controls;
+        document.body.classList.toggle('sticky-controls', stickyControls);
+
     }
 }