perf(LLM任务): 首查短超时快速失败 + 退避抖动 + 标题失败跳过外观识别

生产 24h 数据：外观专利任务 LLM 重试失败 93+82 次几乎全是超时，
终态 41 行降级为「外观识别异常」；成功调用 p99=34s、超 60s 仅 0.02%。
原策略每轮重试都挂满 90s（被全局 call-timeout 钳制），且 1.5s/3s
密集重试整批落在同一劣化窗口内。

- 第 1 次尝试改用 llm-first-attempt-read-timeout-millis（默认 60s）快速失败，
  重试走完整读超时，慢而成功的正常调用不被误杀
- 重试等待改 LlmRetryBackoff：2s/10s + ±30% 抖动，覆盖更长窗口并打散同批尖峰
- 外观专利标题识别失败时跳过外观请求（该行必走回退，外观结果本就会被丢弃）

backend-java/src/main/resources/application.yml

@@ -251,6 +251,7 @@ aiimage:
     llm-max-tokens: ${AIIMAGE_APPEARANCE_PATENT_LLM_MAX_TOKENS:64000}
     llm-connect-timeout-millis: ${AIIMAGE_APPEARANCE_PATENT_LLM_CONNECT_TIMEOUT_MILLIS:10000}
     llm-read-timeout-millis: ${AIIMAGE_APPEARANCE_PATENT_LLM_READ_TIMEOUT_MILLIS:180000}
+    llm-first-attempt-read-timeout-millis: ${AIIMAGE_APPEARANCE_PATENT_LLM_FIRST_ATTEMPT_READ_TIMEOUT_MILLIS:60000}
     llm-batch-size: ${AIIMAGE_APPEARANCE_PATENT_LLM_BATCH_SIZE:10}
     llm-row-concurrency: ${AIIMAGE_APPEARANCE_PATENT_LLM_ROW_CONCURRENCY:10}
     max-parse-rows: ${AIIMAGE_APPEARANCE_PATENT_MAX_PARSE_ROWS:50000}
@@ -283,6 +284,7 @@ aiimage:
     llm-max-tokens: ${AIIMAGE_SIMILAR_ASIN_LLM_MAX_TOKENS:64000}
     llm-connect-timeout-millis: ${AIIMAGE_SIMILAR_ASIN_LLM_CONNECT_TIMEOUT_MILLIS:10000}
     llm-read-timeout-millis: ${AIIMAGE_SIMILAR_ASIN_LLM_READ_TIMEOUT_MILLIS:180000}
+    llm-first-attempt-read-timeout-millis: ${AIIMAGE_SIMILAR_ASIN_LLM_FIRST_ATTEMPT_READ_TIMEOUT_MILLIS:60000}
     llm-retry-times: ${AIIMAGE_SIMILAR_ASIN_LLM_RETRY_TIMES:3}
     llm-row-concurrency: ${AIIMAGE_SIMILAR_ASIN_LLM_ROW_CONCURRENCY:5}
     llm-image-download-timeout-seconds: ${AIIMAGE_SIMILAR_ASIN_LLM_IMAGE_DOWNLOAD_TIMEOUT_SECONDS:10}