feat(wechat): add subscribe morning reminder, plaza welcome, and LLM fallback

Enable daily morning greeting on reply 1 (with custom time, modify, and cancel),
random greeting delivery, M发现 in subscribe welcome, and optional LLM parsing when
rules miss. Also fix WeChat MP draft/config error passthrough and add Tang E2E scripts.

Co-authored-by: Cursor <cursoragent@cursor.com>

.env.example

@@ -199,6 +199,12 @@ H5_PUBLIC_BASE_URL=http://127.0.0.1:5173
 # MEMIND_WECHAT_SCHEDULE_LLM_MODEL_PROVIDER_KEY_ID=
 # MEMIND_WECHAT_SCHEDULE_LLM_MODEL=deepseek-v4-pro
 
+# 每日早安订阅：规则未命中时的 LLM 兜底（改时间/取消/自然语言确认）
+# H5_WECHAT_SUBSCRIBE_MORNING_LLM_ENABLED=0
+# MEMIND_WECHAT_SUBSCRIBE_MORNING_LLM_MODEL_PROVIDER_KEY_ID=
+# MEMIND_WECHAT_SUBSCRIBE_MORNING_LLM_MODEL=deepseek-v4-flash
+# MEMIND_WECHAT_SUBSCRIBE_MORNING_LLM_MIN_CONFIDENCE=0.65
+
 # 日程 / 定时自动任务 Worker（到点扫描 DB 并执行；默认跟随 H5_REMINDER_WORKER_ENABLED）
 # H5_SCHEDULE_ENABLED=1
 # H5_REMINDER_WORKER_ENABLED=1