feat: add theme update

app/Http/Controllers/ThemeController.php

@@ -23,4 +23,26 @@ public function show($id)
     {
         return response()->json(Theme::findOrFail($id));
     }
+
+    // Edit an existing theme — typically its color map. The `key` is the stable
+    // identifier the app maps against, so it is intentionally not editable here.
+    public function update(Request $request, $id)
+    {
+        $theme = Theme::findOrFail($id);
+
+        $data = $request->validate([
+            'name' => 'sometimes|string|max:255',
+            'colors' => 'sometimes|array',
+            'colors.*' => 'nullable|string|max:32',
+            'order' => 'sometimes|integer',
+            'is_active' => 'sometimes|boolean',
+        ]);
+
+        $theme->update($data);
+
+        return response()->json([
+            'message' => 'Theme updated successfully',
+            'data' => $theme,
+        ]);
+    }
 }