Summary

Upgrade the @angular/platform-browser dependency from version 19.2.14 to
21.0.5 in the frontend.

Related PR

• Bump @angular/platform-browser from 19.2.14 to 21.0.5 in /frontend #1890

Parent Issue

• [Features parity] Dependencies #1817

Details

This is a major version upgrade created by Dependabot. Angular 21 includes:

• Signal forms improvements and fixes
• Performance optimizations
• Various bug fixes and improvements