feat(aws-compat): queue attributes for Terraform (FifoQueue, ContentBasedDeduplication, Policy, real timestamps)

- GetQueueAttributes now returns FifoQueue, ContentBasedDeduplication, Policy and
  real Created/LastModifiedTimestamp (previously missing/stubbed '0000000000')
- Queue: add CreatedAt, LastModifiedAt, Policy, ContentBasedDeduplication
- parse FifoQueue/ContentBasedDeduplication in both protocols (StringToBool)
- Policy/RedriveAllowPolicy: normalize JSON-string form to object (JSON protocol
  sent them as string -> SetQueueAttributes failed with InvalidParameterValue)
- persistence: keep new fields in meta DTO + backfill empty timestamps on load
- FIFO dedup is inherent: IsDuplicate/InitDuplicatation gate on IsFIFO only
  (env flag EnableDuplicates=false disabled dedup for all FIFO queues)

app/models/conversions.go

@@ -34,3 +34,31 @@ func (s *StringToInt) UnmarshalJSON(data []byte) error {
 func (s *StringToInt) Int() int {
 	return int(*s)
 }
+
+// StringToBool — аналог StringToInt для булевых атрибутов: принимает и JSON-bool
+// (true/false), и строку ("true"/"false"). Query-протокол шлёт строки,
+// JSON-протокол — булевы значения; без этого FifoQueue/ContentBasedDeduplication
+// из JSON-запроса молча терялись бы.
+type StringToBool bool
+
+func (s *StringToBool) UnmarshalJSON(data []byte) error {
+	var b bool
+	if err := json.Unmarshal(data, &b); err == nil {
+		*s = StringToBool(b)
+		return nil
+	}
+	var str string
+	if err := json.Unmarshal(data, &str); err != nil {
+		return err
+	}
+	tmp, err := strconv.ParseBool(str)
+	if err != nil {
+		return err
+	}
+	*s = StringToBool(tmp)
+	return nil
+}
+
+func (s *StringToBool) Bool() bool {
+	return bool(*s)
+}