refactor(services): migrate user and applications services to auth domain

Update _apiDomain in UserService (/cms → /auth) and ApplicationsService
(/skydive → /auth) following the backend route reorganization.

fix(calculator): use nullish coalescing for currentUser.poids to preserve
default weight when no skydiver profile exists

docs: update README

src/app/components/calculator/calculator.component.ts

@@ -144,7 +144,7 @@ export class CalculatorComponent implements OnInit, OnDestroy {
                     lastjump$.subscribe((jump) => {
                         this.lastjump = jump;
                         this.inputs.jumps = jump.numero;
-                        this.inputs.weight = this.currentUser.poids!;
+                        this.inputs.weight = this.currentUser.poids ?? this.inputs.weight;
                         this.inputs.current = jump.taille!;
                         this.canopy_size_table = new MatTableDataSource<WeightSize>(weightSizes);
                         this.refresh();

src/app/core/services/applications.service.ts

@@ -10,7 +10,7 @@ import { map } from 'rxjs/operators';
 export class ApplicationsService {
     private apiService = inject(ApiService);
 
-    private _apiDomain = '/skydive';
+    private _apiDomain = '/auth';
 
     query(config: ApplicationListConfig): Observable<ApplicationList> {
         // Convert any filters over to Angular's URLSearchParams

src/app/core/services/user.service.ts

@@ -19,7 +19,7 @@ export class UserService implements OnDestroy {
     private isAuthenticatedSubject = new ReplaySubject<boolean>(1);
     public isAuthenticated = this.isAuthenticatedSubject.asObservable();
 
-    private _apiDomain = '/cms';
+    private _apiDomain = '/auth';
 
     ngOnDestroy() {
         this._subcriptions.forEach((subscription: Subscription) => subscription.unsubscribe());