feat(api): Memory compaction 管线与调度修复，同步环境变量示例

Memory compaction（近重复 chunk 软排除）
- 新增 compaction 调度：Redis debounce、scheduler gate、增量游标；任务结束时 finalize，避免 gate 长期占用并处理运行期新 trigger。
- Celery memory_compaction_run：debounce 未到点则 retry；用户级 Redis 锁；成功路径更新游标并 finalize；异常时释放 scheduler gate 并 self.retry，避免静默卡死调度与瞬时失败不重试。
- compaction_service：多层判定 + canonical 打分；无 embedding 时停止前移游标（awaiting_embeddings）；curation details 补全 trigger 等上下文。
- ingest_transcript_sync：同步路径尽力写入 embedding，与异步 ingest 行为对齐，避免 compaction 永远扫不到无向量 chunk。
- repo：新增 update_chunk_embedding_sync。
测试
- 扩展 test_memory_compaction：调度合并、finalize、ingest embedding、无向量游标、异常路径 gate+retry 等回归用

api/app/features/memory/service.py

@@ -9,6 +9,8 @@ Celery 侧使用 `ingest_transcript_sync` + `retrieve_evidence_sync`，与异步
 `api/docs/memory-retrieval.md`。
 """
 
+import asyncio
+
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.logging import get_logger
@@ -184,13 +186,15 @@ def ingest_transcript_sync(
 ) -> str:
     """
     Sync transcript ingest for Celery tasks.
-    Creates source + chunks + FTS. Skips embedding (async).
+    Creates source + chunks + FTS, and best-effort populates embeddings.
     Returns source_id.
     """
+    from app.core.dependencies import get_embedding_provider
     from app.features.memory.chunker import chunk_transcript
     from app.features.memory.repo import (
         create_chunk_sync,
         create_source_sync,
+        update_chunk_embedding_sync,
         update_chunk_fts_sync,
     )
 
@@ -207,6 +211,7 @@ def ingest_transcript_sync(
     session.flush()
 
     chunks_text = chunk_transcript(transcript.strip())
+    chunk_records: list[tuple[str, str]] = []
     for i, content in enumerate(chunks_text):
         chunk = create_chunk_sync(
             session,
@@ -216,8 +221,22 @@ def ingest_transcript_sync(
             chunk_index=i,
         )
         session.flush()
+        chunk_records.append((chunk.id, content))
         update_chunk_fts_sync(session, chunk.id)
 
+    try:
+        embedding_provider = get_embedding_provider()
+        if chunk_records and embedding_provider is not None:
+            texts = [content for _, content in chunk_records]
+            embeddings = asyncio.run(embedding_provider.embed_texts(texts))
+            for (chunk_id, _), emb in zip(chunk_records, embeddings):
+                if emb:
+                    update_chunk_embedding_sync(session, chunk_id, emb)
+    except Exception as e:
+        logger.warning(
+            "memory embedding 跳过(sync): {} exc_type={}", e, type(e).__name__
+        )
+
     try:
         from app.core.config import settings
         from app.features.memory.enrichment import enrich_memory_after_ingest_sync