refactor(api): TOML 配置 SSOT、统一错误契约、Auth/事务加固与可观测性 (#33)

配置 SSOT（TOML + .env）
统一错误契约
Auth 与事务边界
Redis / Celery 可靠性:业务 Redis（DB/0）与 Celery broker/backend（DB/1）显式拆分；连接池、sync client
可观测性（OpenTelemetry + LGTM）

api/app/features/evaluation/replay_service.py

@@ -10,7 +10,7 @@ from datetime import datetime
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.core.db import utc_now
+from app.core.db import transactional, utc_now
 from app.core.logging import get_logger
 from app.core.security import hash_password
 from app.features.auth import repo as auth_repo
@@ -64,8 +64,8 @@ class ReplayConversationService:
             subscription_type="free",
             created_at=utc_now(),
         )
-        await auth_repo.create_user(user, self._db)
-        await self._db.commit()
+        async with transactional(self._db):
+            await auth_repo.create_user(user, self._db)
         await self._db.refresh(user)
 
         conversation_id = str(uuid.uuid4())
@@ -159,13 +159,6 @@ class ReplayConversationService:
             segment = await conv_service.create_user_segment(conv, conv.user_id, text)
             segment_ids.append(segment.id)
             ts = segment.created_at or conv.last_message_at
-            if not skip_memoir:
-                await memoir_ingest_scheduler.queue_segment(
-                    conv.user_id,
-                    segment.id,
-                    text_char_count=len(text),
-                    trigger="evaluation_replay",
-                )
             await process_user_message(
                 conversation_id=cid,
                 user_message=text,
@@ -175,6 +168,8 @@ class ReplayConversationService:
                 user=user,
                 user_message_timestamp=ts,
                 force_skip_tts=skip_tts,
+                memoir_trigger="evaluation_replay",
+                schedule_memoir=not skip_memoir,
             )
             count += 1