fix: Use original favicons + add typography guidance

- Added favicon.ico and favicon.svg from dealplustech.co.th
- Added typography guidance comment in globals.css
- NO automatic font size changes
- Use .text-base (16px) minimum for readable text

src/styles/globals.css

@@ -68,3 +68,10 @@
     @apply bg-clip-text text-transparent bg-gradient-to-r from-primary-500 to-primary-700;
   }
 }
+
+/*
+ * Typography Best Practices:
+ * - Use .text-base (16px) as minimum for readable text
+ * - Avoid .text-xs (12px) and .text-sm (14px) for body content
+ * - For less emphasis, use color (text-secondary-600) not smaller size
+ */