feat: 添加 Shares 公平共享类型和 SharesService

包含 SharesRespMsg、AssocSharesObjWrap、TRES 明细等类型。SharesService 提供 GetShares 方法，支持按 accounts 和 users 查询。

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

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

internal/slurm/slurm_shares_test.go

@@ -0,0 +1,84 @@
+package slurm
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestSharesService_GetShares(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/shares", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `{"shares": {"shares": [], "total_shares": 100}}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	resp, _, err := client.Shares.GetShares(context.Background(), nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+	if resp.Shares == nil {
+		t.Fatal("expected non-nil shares")
+	}
+	if resp.Shares.TotalShares == nil || *resp.Shares.TotalShares != 100 {
+		t.Errorf("expected total_shares=100, got %v", resp.Shares.TotalShares)
+	}
+}
+
+func TestSharesService_GetShares_WithOptions(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/shares", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		q := r.URL.Query()
+		if q.Get("accounts") != "acc1" {
+			t.Errorf("expected accounts=acc1, got %s", q.Get("accounts"))
+		}
+		if q.Get("users") != "user1" {
+			t.Errorf("expected users=user1, got %s", q.Get("users"))
+		}
+		fmt.Fprint(w, `{"shares": {"shares": [], "total_shares": 50}}`)
+	})
+	server := httptest.NewServer(mux)
+	defer server.Close()
+
+	client, _ := NewClient(server.URL, nil)
+	opts := &GetSharesOptions{
+		Accounts: Ptr("acc1"),
+		Users:    Ptr("user1"),
+	}
+	resp, _, err := client.Shares.GetShares(context.Background(), opts)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp == nil {
+		t.Fatal("expected non-nil response")
+	}
+}
+
+func TestSharesService_GetShares_Error(t *testing.T) {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/slurm/v0.0.40/shares", 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.Shares.GetShares(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)
+	}
+}