feat: record stream interruption reasons via StreamStatus

- Add StreamStatus type (relay/common) to track stream end reason
  (done/timeout/client_gone/scanner_error/eof/panic/ping_fail) and
  accumulate soft errors during streaming via sync.Once + sync.Mutex.
- Add StreamResult (relay/helper) as the callback interface: adapters
  call sr.Error() for soft errors, sr.Stop() for fatal, sr.Done() for
  normal completion. No early-return problem — multiple errors per chunk
  are naturally supported.
- Refactor StreamScannerHandler callback from func(string) bool to
  func(string, *StreamResult). All 9 channel adapters updated.
- Write stream_status into log other JSON field (admin-only) with
  status ok/error, end_reason, error_count, and error messages.
- Frontend: display stream status in log detail expansion for admins.

service/log_info_generate.go

@@ -76,6 +76,7 @@ func GenerateTextOtherInfo(ctx *gin.Context, relayInfo *relaycommon.RelayInfo, m
 	appendFinalRequestFormat(relayInfo, other)
 	appendBillingInfo(relayInfo, other)
 	appendParamOverrideInfo(relayInfo, other)
+	appendStreamStatus(relayInfo, other)
 	return other
 }
 
@@ -86,6 +87,33 @@ func appendParamOverrideInfo(relayInfo *relaycommon.RelayInfo, other map[string]
 	other["po"] = relayInfo.ParamOverrideAudit
 }
 
+func appendStreamStatus(relayInfo *relaycommon.RelayInfo, other map[string]interface{}) {
+	if relayInfo == nil || other == nil || !relayInfo.IsStream || relayInfo.StreamStatus == nil {
+		return
+	}
+	ss := relayInfo.StreamStatus
+	status := "ok"
+	if !ss.IsNormalEnd() || ss.HasErrors() {
+		status = "error"
+	}
+	streamInfo := map[string]interface{}{
+		"status":     status,
+		"end_reason": string(ss.EndReason),
+	}
+	if ss.EndError != nil {
+		streamInfo["end_error"] = ss.EndError.Error()
+	}
+	if ss.ErrorCount > 0 {
+		streamInfo["error_count"] = ss.ErrorCount
+		messages := make([]string, 0, len(ss.Errors))
+		for _, e := range ss.Errors {
+			messages = append(messages, e.Message)
+		}
+		streamInfo["errors"] = messages
+	}
+	other["stream_status"] = streamInfo
+}
+
 func appendBillingInfo(relayInfo *relaycommon.RelayInfo, other map[string]interface{}) {
 	if relayInfo == nil || other == nil {
 		return