fix: disabled-state UI, settings shallow-merge, and popup save reliability

Co-authored-by: Cursor <cursoragent@cursor.com>

popup/popup.js

@@ -115,7 +115,7 @@
     return overrides;
   }
 
-  function saveFromControls() {
+  async function saveFromControls() {
     const settings = {
       enabled: document.getElementById("enabled").checked,
       darkMode: document.getElementById("darkMode").value,
@@ -134,7 +134,11 @@
       }
     });
 
-    window.RedditTweaks.saveSettings(settings);
+    try {
+      await window.RedditTweaks.saveSettings(settings);
+    } catch (err) {
+      console.error("Reddit Tweaks: failed to save settings", err);
+    }
   }
 
   async function init() {