Enhance FileInfo structure and DiskFS functionality

- Added CTime (creation time) and AccessCount fields to FileInfo struct for better file metadata tracking.
- Updated NewFileInfo and NewFileInfoFromOS functions to initialize new fields.
- Enhanced DiskFS to maintain access counts and file metadata, including flushing to JSON files.
- Modified Open and Create methods to increment access counts and set creation times appropriately.
- Updated garbage collection logic to utilize real access counts for files.

vfs/fileinfo.go

@@ -7,27 +7,35 @@ import (
 )
 
 type FileInfo struct {
-	name  string
-	size  int64
-	MTime time.Time
-	ATime time.Time
+	name        string
+	size        int64
+	MTime       time.Time
+	ATime       time.Time
+	CTime       time.Time // Creation time
+	AccessCount int64
 }
 
 func NewFileInfo(key string, size int64, modTime time.Time) *FileInfo {
+	now := time.Now()
 	return &FileInfo{
-		name:  key,
-		size:  size,
-		MTime: modTime,
-		ATime: time.Now(),
+		name:        key,
+		size:        size,
+		MTime:       modTime,
+		ATime:       now,
+		CTime:       now,
+		AccessCount: 0,
 	}
 }
 
 func NewFileInfoFromOS(f os.FileInfo, key string) *FileInfo {
+	now := time.Now()
 	return &FileInfo{
-		name:  key,
-		size:  f.Size(),
-		MTime: f.ModTime(),
-		ATime: time.Now(),
+		name:        key,
+		size:        f.Size(),
+		MTime:       f.ModTime(),
+		ATime:       now,
+		CTime:       now, // Will be overwritten if loaded from disk
+		AccessCount: 0,
 	}
 }