feat: 加固 Agent CLI 执行边界并更新模型目录

收紧 SSH 命令护栏、权限校验与远程执行会话，并同步主流大模型供应商列表。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/pkg/agentcli/tools/ssh_execute_test.go

@@ -0,0 +1,25 @@
+package tools
+
+import (
+	"testing"
+	"time"
+)
+
+func TestBoundedSSHTimeout(t *testing.T) {
+	cases := []struct {
+		name string
+		in   time.Duration
+		want time.Duration
+	}{
+		{name: "non-positive", in: 0, want: time.Second},
+		{name: "normal", in: 60 * time.Second, want: 60 * time.Second},
+		{name: "too-large", in: 24 * time.Hour, want: 300 * time.Second},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := boundedSSHTimeout(tc.in); got != tc.want {
+				t.Fatalf("boundedSSHTimeout(%v)=%v, want %v", tc.in, got, tc.want)
+			}
+		})
+	}
+}