Angular 20+ (LTS) Support

• Upgraded to Angular 20 LTS with full compatibility (Minimum peer dependency remains Angular 19.0.0+).
• Update to TypeScript 5.9.x for improved type safety and performance.
• Modernized dependency injection using inject() function throughout codebase.
• All demo components fully migrated to standalone architecture.
• Updated build tooling to Angular 20 ecosystem.
• Code quality improvements and cleanup.