feat: multi-tenant user delete scope + conditional keycloak wait

- Add GET /users/{user_id}/tenant-count endpoint
- Add scope query param (current|all) to DELETE /users/{user_id}
- UserService.delete_user now supports scope='all' to deactivate/remove
  user from all tenants
- Frontend users.ts: getTenantCount(), delete() accepts scope param
- Frontend +page.svelte: async openDeleteDialog fetches tenant count,
  shows 4-button dialog when user belongs to >1 tenant
- docker-entrypoint.sh: Keycloak wait now conditional on WAIT_FOR_KEYCLOAK=1

frontend/src/lib/api/dashboard/users.ts

@@ -125,14 +125,33 @@ export const usersAPI = {
 		return response.data!;
 	},
 
+	/**
+	 * Retorna en cuántos tenants está registrado el usuario.
+	 */
+	async getTenantCount(userId: string, companyId: number): Promise<number> {
+		const response = await api.get<{ tenant_count: number }>(
+			`/v1/core/users/${userId}/tenant-count?company_id=${companyId}`
+		);
+		if (response.error) {
+			throw new Error(response.error);
+		}
+		return response.data!.tenant_count;
+	},
+
 	/**
 	 * Elimina un usuario
 	 */
-	async delete(userId: string, companyId: number, softDelete: boolean = true): Promise<void> {
+	async delete(
+		userId: string,
+		companyId: number,
+		softDelete: boolean = true,
+		scope: 'current' | 'all' = 'current'
+	): Promise<void> {
 		const queryParams = new URLSearchParams();
 		queryParams.set('company_id', companyId.toString());
 		queryParams.set('soft_delete', softDelete.toString());
-		
+		queryParams.set('scope', scope);
+
 		const response = await api.delete(`/v1/core/users/${userId}?${queryParams}`);
 		if (response.error) {
 			throw new Error(response.error);