fix: add missing colors.xml for Material3 theme

Author: rprabhat

android/app/src/main/res/values/colors.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <!-- Primary brand colors -->
+    <color name="primary">#0066FF</color>
+    <color name="primary_dark">#0052CC</color>
+    <color name="primary_light">#3385FF</color>
+    
+    <!-- Secondary colors -->
+    <color name="secondary">#6B7280</color>
+    <color name="secondary_dark">#4B5563</color>
+    <color name="secondary_light">#9CA3AF</color>
+    
+    <!-- Background colors -->
+    <color name="background">#FFFFFF</color>
+    <color name="surface">#F9FAFB</color>
+    <color name="surface_variant">#F3F4F6</color>
+    
+    <!-- Text colors -->
+    <color name="on_primary">#FFFFFF</color>
+    <color name="on_secondary">#FFFFFF</color>
+    <color name="on_background">#111827</color>
+    <color name="on_surface">#374151</color>
+    
+    <!-- Status colors -->
+    <color name="error">#DC2626</color>
+    <color name="success">#16A34A</color>
+    <color name="warning">#F59E0B</color>
+</resources>