Add performance filtering by date range

Introduces a new API method in HttpService to fetch performances by a date filter. ScheduleComponent now generates a date filter for the next 14 days and loads performances using the new filtered endpoint, improving flexibility for bookable days.

src/app/http.service.ts

@@ -51,6 +51,11 @@ export class HttpService {
     return this.http.get<Vorstellung>(`${this.baseUrl}vorstellung/${id}`);
   }
 
+  /* POST /api/vorstellung/filter */
+  getPerformaceByFilter(filter: string[]): Observable<Vorstellung[]> {
+    return this.http.post<Vorstellung[]>(`${this.baseUrl}vorstellung/filter`, filter);
+  }
+
   /* POST /api/vorstellung */
   addPerformace(vorstellung: Omit<Vorstellung, 'id'>): Observable<Vorstellung> {
     return this.http.post<Vorstellung>(`${this.baseUrl}vorstellung`, vorstellung);
@@ -67,7 +72,7 @@ export class HttpService {
   }
 
 
-  /* Vorstellung APIs */
+  /* Film APIs */
 
   /* GET /api/film */
   getMovies(): Observable<Film[]> {