feat: 添加 Partition 领域类型和 PartitionsService

包含 PartitionInfo 及其子结构体（Nodes、Accounts、Groups、QOS、TRES、CPUs、Defaults、Maximums、Minimums、Priority、Timeouts）。PartitionsService 提供 GetPartitions 和 GetPartition 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_partitions_test.go

@@ -0,0 +1,111 @@
+package slurm
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+)
+
+func TestPartitionsService_GetPartitions(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/partitions", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"partitions": [], "last_update": {}}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.Partitions.GetPartitions(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestPartitionsService_GetPartitions_WithOptions(t *testing.T) {
+	var capturedQuery url.Values
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/partitions", func(w http.ResponseWriter, r *http.Request) {
+		capturedQuery = r.URL.Query()
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"partitions": [], "last_update": {}}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	opts := &GetPartitionsOptions{
+		UpdateTime: Ptr(int64(1700000000)),
+	}
+	_, _, err := client.Partitions.GetPartitions(context.Background(), opts)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if capturedQuery.Get("update_time") != "1700000000" {
+		t.Errorf("expected update_time=1700000000, got %s", capturedQuery.Get("update_time"))
+	}
+}
+
+func TestPartitionsService_GetPartition(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/partition/gpu", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"partitions": [{"name": "gpu"}], "last_update": {}}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.Partitions.GetPartition(context.Background(), "gpu", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+	if resp.Partitions == nil || len(*resp.Partitions) != 1 {
+		t.Fatalf("expected 1 partition, got %v", resp.Partitions)
+	}
+}
+
+func TestPartitionsService_GetPartitions_Error(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/partitions", 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.Partitions.GetPartitions(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 TestPartitionsService_GetPartition_Error(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/partition/nonexistent", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		fmt.Fprint(w, `{"errors": [{"error": "partition not found"}]}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	_, _, err := client.Partitions.GetPartition(context.Background(), "nonexistent", nil)
+	if err == nil {
+		t.Fatal("expected error for 404 response")
+	}
+}