uploads,tools,config,main: 将 upload_file 返回路径改为服务器端绝对路径并透传给 spark_submit

之前 upload_file 把文件写到 DataDir/uploads/<filename>，返回相对路径
uploads/hello.txt。MCP 服务器与 agent 不在同一台机器，agent 无法构造服务
器本地路径，因此 spark_submit 无法定位脚本。

改为由新的 internal/uploads 包 mint 一个 32 字符十六进制 file_id，文件落盘为
DataDir/uploads/<file_id>，元数据写入 <file_id>.meta.json（原始文件名只存在
sidecar 里）。upload_file 返回 {file_id, path, name, size, sha256}，其中 path
是绝对路径。spark_submit 的 description 明确要求 LLM 直接把 upload_file 返回
的 path 放进 args，不要自己构造路径。

为什么只在描述里约束而不在代码里拒绝非 mint 的绝对路径：集群本地已有路径
（如 /opt/spark/examples/pi.py）是合法的 spark-submit 参数，代码不能替
LLM 拒绝。

测试锁定：
- internal/uploads: Save 往返、AbsPath/Validate 非法路径、Sweep 过期/未过期/
  孤立 sidecar
- internal/mcp/tools: upload_file 新响应字段、spark_submit 透传 mint 路径与
  集群本地路径

刻意未做：S3/HDFS 上传、给 spark_submit 新增 file_id 参数、在代码层面拒绝
集群本地绝对路径。

破坏性变更：upload_file 响应从相对 path 改为绝对 path，并新增 file_id/name/
sha256 字段。该工具尚无外部调用者。

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

internal/mcp/tools/fetch_upload_test.go

@@ -8,6 +8,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 	"testing"
@@ -18,6 +19,7 @@ import (
 	"spark-mcp-go/internal/cluster"
 	"spark-mcp-go/internal/httpclient"
 	"spark-mcp-go/internal/storage"
+	"spark-mcp-go/internal/uploads"
 )
 
 // testDepsWithDataDir returns dependencies backed by an in-memory DB and a
@@ -30,6 +32,12 @@ func testDepsWithDataDir(t *testing.T) (*Deps, *storage.ClusterRepo) {
 	}
 	t.Cleanup(func() { _ = db.Close() })
 
+	dataDir := t.TempDir()
+	uploadStore, err := uploads.New(filepath.Join(dataDir, "uploads"))
+	if err != nil {
+		t.Fatalf("new upload store: %v", err)
+	}
+
 	return &Deps{
 		HTTPClient: httpclient.New(httpclient.Config{
 			Timeout:          5 * time.Second,
@@ -37,7 +45,8 @@ func testDepsWithDataDir(t *testing.T) (*Deps, *storage.ClusterRepo) {
 		}),
 		ClusterRepo:      db.Clusters(),
 		MaxResponseBytes: 1 << 20,
-		DataDir:          t.TempDir(),
+		DataDir:          dataDir,
+		UploadStore:      uploadStore,
 	}, db.Clusters()
 }
 
@@ -324,15 +333,26 @@ func TestUploadFile(t *testing.T) {
 	}
 
 	payload := resultJSON(t, res)
-	if payload["path"] != "uploads/hello.txt" {
-		t.Errorf("path=%v, want uploads/hello.txt", payload["path"])
+	fileID, ok := payload["file_id"].(string)
+	if !ok || !regexp.MustCompile(`^[0-9a-f]{32}$`).MatchString(fileID) {
+		t.Errorf("file_id=%v, want 32 lowercase hex chars", payload["file_id"])
+	}
+	path, ok := payload["path"].(string)
+	if !ok || !filepath.IsAbs(path) || !strings.HasSuffix(path, "/"+fileID) {
+		t.Errorf("path=%v, want absolute path ending in /%s", payload["path"], fileID)
+	}
+	if payload["name"] != "hello.txt" {
+		t.Errorf("name=%v, want hello.txt", payload["name"])
 	}
 	if payload["size"] != float64(len("hello world")) {
 		t.Errorf("size=%v, want %d", payload["size"], len("hello world"))
 	}
+	sha, ok := payload["sha256"].(string)
+	if !ok || !regexp.MustCompile(`^[0-9a-f]{64}$`).MatchString(sha) {
+		t.Errorf("sha256=%v, want 64-char hex", payload["sha256"])
+	}
 
-	final := filepath.Join(deps.DataDir, "uploads", "hello.txt")
-	got, err := os.ReadFile(final)
+	got, err := os.ReadFile(path)
 	if err != nil {
 		t.Fatalf("read uploaded file: %v", err)
 	}
@@ -340,7 +360,7 @@ func TestUploadFile(t *testing.T) {
 		t.Errorf("content=%q, want %q", got, "hello world")
 	}
 
-	info, err := os.Stat(final)
+	info, err := os.Stat(path)
 	if err != nil {
 		t.Fatalf("stat uploaded file: %v", err)
 	}
@@ -393,9 +413,19 @@ func TestUploadFile_Base64(t *testing.T) {
 		t.Fatalf("handler error: %v", err)
 	}
 
-	_ = resultJSON(t, res)
-	final := filepath.Join(deps.DataDir, "uploads", "hello.bin")
-	got, err := os.ReadFile(final)
+	payload := resultJSON(t, res)
+	path, ok := payload["path"].(string)
+	if !ok || !filepath.IsAbs(path) {
+		t.Errorf("path=%v, want absolute path", payload["path"])
+	}
+	if payload["name"] != "hello.bin" {
+		t.Errorf("name=%v, want hello.bin", payload["name"])
+	}
+	if payload["size"] != float64(len("hello")) {
+		t.Errorf("size=%v, want %d", payload["size"], len("hello"))
+	}
+
+	got, err := os.ReadFile(path)
 	if err != nil {
 		t.Fatalf("read uploaded file: %v", err)
 	}