Moved to uv from poetry

Updated ruff and mypy, accepted all changes
Central exception management and injected the Session.
This removed a lot of duplicated boilerplate code.
Added health check
Updated to Angular 21

overlord/src/app/period/period-detail/period-detail.component.ts

@@ -35,7 +35,7 @@ export class PeriodDetailComponent implements OnInit {
   item: Period = new Period();
 
   @HostListener('window:keydown.f2', ['$event'])
-  focusDate(event: KeyboardEvent) {
+  focusDate(event: Event) {
     event.preventDefault();
     this.startDate.nativeElement.focus();
     this.startDate.nativeElement.select();