umpires can be added to courts as umpires (removal also)

src/app/services/court.umpire.service.ts

@@ -0,0 +1,56 @@
+import { Injectable } from '@angular/core';
+import { toSignal } from '@angular/core/rxjs-interop';
+import { CourtUmpire, db } from 'db';
+import { liveQuery } from 'dexie';
+import { from } from 'rxjs';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class CourtUmpireService {
+  /**
+   * All court umpires (reactive)
+   */
+  readonly umpires = toSignal(
+    from(liveQuery(() => db.courtUmpires.orderBy('courtNo').toArray())),
+    { initialValue: [] }
+  );
+
+  /**
+   * Get by court number (reactive single)
+   */
+  getByCourtNo(courtNo: number) {
+    return toSignal<CourtUmpire | undefined>(
+      liveQuery(() => db.courtUmpires.where('courtNo').equals(courtNo).first()),
+      { initialValue: undefined }
+    );
+  }
+
+  /**
+   * Create / update
+   */
+  async save(item: Omit<CourtUmpire, 'id'>): Promise<number> {
+    return db.courtUmpires.add(item as CourtUmpire);
+  }
+
+  async update(id: number, changes: Partial<CourtUmpire>): Promise<number> {
+    return db.courtUmpires.update(id, changes);
+  }
+
+  async delete(id: number): Promise<void> {
+    await db.courtUmpires.delete(id);
+  }
+
+  async removeByUmpireId(umpireId: number): Promise<void> {
+    const item = await db.courtUmpires
+      .where('umpireId')
+      .equals(umpireId)
+      .first();
+
+    if (!item?.id) {
+      return;
+    }
+
+    await db.courtUmpires.delete(item.id);
+  }
+}