Phase 5 Batch 2: 4 RM Tool + rm 客户端 + 日志降级链

- internal/rm/client.go: YARN RM 客户端
  - ListApps / GetApp / KillApp / GetLogs
  - GetLogs 降级链数据驱动 (amContainerLogs → aggregated-logs → logs)
  - 跨主机 redirect 保留 Authorization (URLAllowlist 兜底)
- 4 Tool: list_applications / get_application_status /
  get_application_logs / kill_application
  - mcp.WithEnum(state) 约束 YARN app 状态
  - tool handler 永远 (result, nil), 业务错误用 NewToolResultError
- deps.go: +HTTPClient + MaxResponseBytes
- main.go: 注入 httpclient.Client
- 端到端实测: mock RM 验证 4 Tool + 降级链 + 错误路径

Co-Authored-By: Claude <noreply@anthropic.com>

internal/mcp/server.go

@@ -0,0 +1,36 @@
+package mcp
+
+import (
+	"net/http"
+
+	"github.com/mark3labs/mcp-go/server"
+
+	"spark-mcp-go/internal/mcp/tools"
+)
+
+// NewServer builds the MCP server with all configured Tools.
+func NewServer(deps *tools.Deps) *server.MCPServer {
+	s := server.NewMCPServer("spark-mcp-go", "0.0.0",
+		server.WithToolCapabilities(false),
+		server.WithRecovery(),
+		server.WithLogging(),
+	)
+	s.AddTool(tools.NewListClustersTool(), deps.ListClustersHandler)
+	s.AddTool(tools.NewSparkSubmitTool(), deps.SparkSubmitHandler)
+	s.AddTool(tools.NewListApplicationsTool(), deps.ListApplicationsHandler)
+	s.AddTool(tools.NewGetApplicationStatusTool(), deps.GetApplicationStatusHandler)
+	s.AddTool(tools.NewGetApplicationLogsTool(), deps.GetApplicationLogsHandler)
+	s.AddTool(tools.NewKillApplicationTool(), deps.KillApplicationHandler)
+	s.AddTool(tools.NewFetchURLTool(), deps.FetchURLHandler)
+	s.AddTool(tools.NewUploadFileTool(), deps.UploadFileHandler)
+	s.AddTool(tools.NewFetchSparkMetricsTool(), deps.FetchSparkMetricsHandler)
+	s.AddTool(tools.NewFetchClusterEnvTool(), deps.FetchClusterEnvHandler)
+	s.AddTool(tools.NewAnalyzeSparkLogTool(), deps.AnalyzeSparkLogHandler)
+	return s
+}
+
+// Handler exposes the MCP server as an http.Handler for main.go to mount.
+func Handler(deps *tools.Deps) (http.Handler, error) {
+	s := NewServer(deps)
+	return server.NewStreamableHTTPServer(s), nil
+}