feat(metadata): enhance metadata handling by sanitizing extracted data and updating documentation for file storage

internal/tools/files.go

@@ -243,11 +243,32 @@ func splitDataURL(value string) (contentBase64 string, mediaType string) {
 }
 
 func decodeBase64(value string) ([]byte, error) {
-	decoded, err := base64.StdEncoding.DecodeString(value)
-	if err == nil {
-		return decoded, nil
+	cleaned := strings.Map(func(r rune) rune {
+		switch r {
+		case ' ', '\t', '\n', '\r':
+			return -1
+		default:
+			return r
+		}
+	}, value)
+
+	encodings := []*base64.Encoding{
+		base64.StdEncoding,
+		base64.RawStdEncoding,
+		base64.URLEncoding,
+		base64.RawURLEncoding,
 	}
-	return base64.RawStdEncoding.DecodeString(value)
+
+	var lastErr error
+	for _, encoding := range encodings {
+		decoded, err := encoding.DecodeString(cleaned)
+		if err == nil {
+			return decoded, nil
+		}
+		lastErr = err
+	}
+
+	return nil, lastErr
 }
 
 func normalizeMediaType(explicit string, fromDataURL string, content []byte) string {