Add SURYA_STREAM_MODE streaming (off/on/abort) for chat completions

- _generate_one_stream: streams responses, optional live repeat-loop
  detection (abort) that closes the stream early and flags the partial
  result as repeat=True so the existing retry loop re-runs with higher
  temperature
- _should_retry honors result.repeat; stream_mode threaded through both
  first attempt and retry calls in chat_completions_batch
- GenerationResult.repeat field; SURYA_STREAM_MODE setting (default off)
- diagnostic retry logs (reason=repeat|error|detected, temp)
- docker-compose: SURYA_STREAM_MODE=off, 4090 GPU profile, logs volume
- logger.yaml: TimedRotatingFileHandler for error handler (fixes startup
  crash without maxBytes)

logger.yaml

@@ -18,12 +18,14 @@ handlers:
     interval: 1
     backupCount: 30
   error_file_handler:
-    class: logging.handlers.RotatingFileHandler
+    class: logging.handlers.TimedRotatingFileHandler
     level: ERROR
     formatter: simple
     filename: logs/errors.log
-    backupCount: 20
     encoding: utf8
+    when: d
+    interval: 1
+    backupCount: 20
 root:
     level: INFO
     handlers: [console, info_file_handler, error_file_handler]