feat: add filemanager session and crypto version detection (#516)

* feat: add filemanager session and crypto version detection

* refactor: move copy logic into filemanager, remove fileutil dependency

* fix: apply review suggestions for filemanager

* feat: add Windows locked file tests, fix readFileContent with ReadFile+FileMapping fallback

* fix: remove self-PID skip in findFileHandle to fix Windows CI test

* fix: seek to file start before reading duplicated handle

* fix: use full path matching in findFileHandle to avoid cross-app handle collision

* test: enhance Windows copyLocked tests with write-then-read, large file, and normal copy scenarios

* fix: check all errors in Windows tests, use bytes.Equal for large file comparison

* fix: use stable path suffix matching to handle Windows short path names in CI

filemanager/copy.go

@@ -0,0 +1,35 @@
+package filemanager
+
+import (
+	"os"
+	"strings"
+
+	cp "github.com/otiai10/copy"
+)
+
+// copyFile copies a single file from src to dst.
+func copyFile(src, dst string) error {
+	data, err := os.ReadFile(src)
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(dst, data, 0o600)
+}
+
+// copyDir copies a directory from src to dst, skipping files
+// whose path ends with the skip suffix (e.g. "lock").
+func copyDir(src, dst, skip string) error {
+	opts := cp.Options{Skip: func(info os.FileInfo, src, _ string) (bool, error) {
+		return strings.HasSuffix(strings.ToLower(src), skip), nil
+	}}
+	return cp.Copy(src, dst, opts)
+}
+
+// isFileExists checks if a file (not directory) exists at the given path.
+func isFileExists(path string) bool {
+	info, err := os.Stat(path)
+	if err != nil {
+		return false
+	}
+	return !info.IsDir()
+}