fix: mark per-subreddit mode dirty on color picker change

Without this, new subreddit entries would not persist their color
overrides because _dirtyModes was never set when picking via the
custom color picker.

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

popup/popup.js

@@ -33,7 +33,7 @@
     el.style.backgroundColor = val;
   }
 
-  function openPickerForSwatch(swatchEl) {
+  function openPickerForSwatch(swatchEl, onBeforeChange) {
     if (!picker) {
       picker = window.RedditTweaks.colorPicker.create();
     }
@@ -50,6 +50,7 @@
 
     picker.open(getColorValue(swatchEl), function (hex) {
       setColorValue(swatchEl, hex);
+      if (onBeforeChange) onBeforeChange();
       saveFromControls();
     });
   }
@@ -161,7 +162,9 @@
 
     [bgSwatch, borderSwatch, textSwatch].forEach(function (swatch) {
       swatch.addEventListener("click", function () {
-        openPickerForSwatch(swatch);
+        openPickerForSwatch(swatch, function () {
+          entry._dirtyModes[modeSelect.value] = true;
+        });
       });
     });