[Glitch] Fix categorised custom emojis missing from the emoji picker

Port b4be90f9ea3e29e166b4fb0d0e0cc6b32dbf908b to glitch-soc

Signed-off-by: Hanage999 <hanage999@crazynewworld.net>
Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/features/emoji/picker.ts

@@ -103,7 +103,9 @@ const selectPickerData = createAppSelector(
       categories: [
         'recent',
         'custom',
-        ...Object.keys(categories).toSorted(),
+        ...Object.keys(categories)
+          .toSorted()
+          .map((category) => `custom-${category}`),
         ...defaultCategories,
       ] as CategoryName[],
     };