Enhance styling guidelines to prioritize Angular Material components and discourage unstyled native elements

AGENTS.md

@@ -84,6 +84,8 @@ Use the single-context documentation layout. See [domain.md](file:///home/nessar
 
 ### Styling and user experience
 
+- Use Angular Material components by default whenever they cover the UI need.
+- Never use unstyled native buttons or browser-native dialogs; use Angular Material button directives and `MatDialog` instead.
 - Reuse the existing design system, shared components, spacing rules, and design tokens.
 - Avoid duplicating styles already provided by shared components.
 - Keep component styles scoped unless a style is intentionally global.