feat: 添加 Reservation 领域类型和 ReservationsService

包含 ReservationInfo、ReservationCoreSpec 等类型。ReservationsService 提供 GetReservations 和 GetReservation 2 个方法。

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

internal/slurm/slurm_reservations_test.go

@@ -0,0 +1,86 @@
+package slurm
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestReservationsService_GetReservations(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/reservations", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"reservations": []}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.Reservations.GetReservations(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestReservationsService_GetReservation(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/reservation/test-reservation", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"reservations": [{"name": "test-reservation"}]}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.Reservations.GetReservation(context.Background(), "test-reservation", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+	if resp.Reservations == nil {
+		t.Fatal("expected non-nil reservations")
+	}
+}
+
+func TestReservationsService_GetReservations_Error(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/reservations", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		fmt.Fprint(w, `{"errors": [{"error": "internal error"}]}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	_, _, err := client.Reservations.GetReservations(context.Background(), nil)
+	if err == nil {
+		t.Fatal("expected error for 500 response")
+	}
+	if !strings.Contains(err.Error(), "500") {
+		t.Errorf("expected error to contain 500, got %v", err)
+	}
+}
+
+func TestReservationsService_GetReservation_Error(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/reservation/nonexistent", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprint(w, `{"errors": [{"error": "reservation not found"}]}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	_, _, err := client.Reservations.GetReservation(context.Background(), "nonexistent", nil)
+	if err == nil {
+		t.Fatal("expected error for 404 response")
+	}
+}