feat: add file deduplication and hash checking for uploads

- Implemented SHA-256 hashing for uploaded files to enable deduplication.
- Added CheckHash method to verify if a file with the same hash already exists.
- Updated Upload method to reuse existing media assets if a duplicate is found.
- Introduced a new hash column in the media_assets table to store file hashes.
- Enhanced the upload process to include progress tracking and hash calculation.
- Modified frontend to check for existing files before uploading and to show upload progress.
- Added vuedraggable for drag-and-drop functionality in the content editing view.

backend/tests/storage_test.go

@@ -14,27 +14,27 @@ func TestStorageProvider(t *testing.T) {
 		// Mock Config to match what we expect in config.toml
 		// We use a map to simulate how unmarshal might see it, or just use the Config struct directly if we can manual init.
 		// But provider uses UnmarshalConfig.
-		
+
 		// To test properly, we should try to boot the provider or check the logic.
 		// Let's manually init the Storage struct with the config we expect to be loaded.
-		
+
 		cfg := &storage.Config{
 			Type:      "local",
 			LocalPath: "./storage",
 			Secret:    "your-storage-secret",
 			BaseURL:   "http://localhost:8080/v1/storage",
 		}
-		
+
 		s := &storage.Storage{Config: cfg}
-		
+
 		Convey("SignURL should return absolute URL with BaseURL", func() {
 			key := "test.png"
 			url, err := s.SignURL("GET", key, 1*time.Hour)
 			So(err, ShouldBeNil)
-			
+
 			// Log for debugging
 			t.Logf("Generated URL: %s", url)
-			
+
 			So(url, ShouldStartWith, "http://localhost:8080/v1/storage/test.png")
 			So(url, ShouldContainSubstring, "sign=")
 		})