Modernize client: zoneless change detection + drop .component suffix

[sis0k0]

Summary

Adopts two current Angular conventions in the client app (Angular 22).

Zoneless change detection

• Add provideZonelessChangeDetection() in app.config.ts.
• Remove the zone.js polyfill from angular.json (build + testing configs) and drop the zone.js dependency from package.json.
• Simplify main.ts / main.server.ts — bootstrap no longer wires up provideZoneChangeDetection.

Drop the .component file suffix (v20+ naming)

Renamed files and their classes:

Before	After
app.component.ts / AppComponent	app.ts / App
employees-list.component.ts / EmployeesListComponent	employees-list.ts / EmployeesList
employee-form.component.ts / EmployeeFormComponent	employee-form.ts / EmployeeForm
add-employee.component.ts / AddEmployeeComponent	add-employee.ts / AddEmployee
edit-employee.component.ts / EditEmployeeComponent	edit-employee.ts / EditEmployee

All imports/usages in app.routes.ts and the components updated accordingly.

Verification

• npm run build succeeds (zone.js polyfill bundle gone; SSR prerender still works).
• Ran the full stack against local MongoDB and drove CRUD in a real browser (Playwright): list/add/edit/delete all work with zero JS errors; SSR renders the list with live data.