fix file naming sanitisation

internal/util/util.go

@@ -1,6 +1,9 @@
 package util
 
-import "fmt"
+import (
+	"fmt"
+	"strings"
+)
 
 func HumanSize(size int64) string {
 	const unit = 1024
@@ -17,3 +20,24 @@ func HumanSize(size int64) string {
 		"KMGTPE"[exp],
 	)
 }
+
+func SafeFilename(name string) string {
+	name = strings.TrimSpace(name)
+
+	out := make([]rune, 0, len(name))
+	for _, r := range name {
+		// block control chars (incl CR/LF/TAB), DEL, quotes, backslash
+		if r < 32 || r == 127 || r == '"' || r == '\\' {
+			continue
+		}
+		out = append(out, r)
+	}
+	if len(out) == 0 {
+		return "file"
+	}
+	// optional: cap length
+	if len(out) > 200 {
+		out = out[:200]
+	}
+	return string(out)
+}