feat(api): 访谈路径轻量门控、Memoir Phase1 批处理与叙事/记忆管线加固

- 新增 utterance_substance：短时/应答/元话语可跳过记忆检索、阶段 LLM 与资料抽取 LLM；可配置
- 输入归一化：LLM 模式默认仅语音/ASR；配置项写入 .env.example
- Memoir Phase1：可选 batch LLM 一次性抽取+分类（失败回退逐段）；Extraction 空槽位时阶段与 current_stage 对齐，prompt 约束收紧
- 叙事与忠实度：narrative_safety、证据重叠/场合锚点、标题 slots 与履历短语 grounded；fidelity 解析失败 fail-open 可配置
- 章节管线：锁 TTL 上调、锁竞争 Celery 重试、Phase2 immediate singleflight 等；story_pipeline_sync / chapter_compose / memoir_tasks 联动
- Memory：compaction / repo / summarizer / evidence 小修；事实 FTS 未命中是否回退最近事实可配置
- 新增 memoir_pipeline_trace；补充 memoir_reliability 文档与多项回归/门控测试

api/tests/test_memoir_idempotency.py

@@ -0,0 +1,42 @@
+"""Memoir 链路：correlation id 与 Phase2 派发 task_id 策略。"""
+
+from __future__ import annotations
+
+from app.core.memoir_pipeline_trace import (
+    effective_correlation_id,
+    new_memoir_correlation_id,
+)
+from app.tasks.memoir_tasks import _phase2_immediate_task_id
+
+
+def test_effective_correlation_id_prefers_explicit() -> None:
+    assert (
+        effective_correlation_id(explicit="  cid-1  ", celery_task_id="task-9")
+        == "cid-1"
+    )
+
+
+def test_effective_correlation_id_falls_back_to_celery_task_id() -> None:
+    assert effective_correlation_id(explicit=None, celery_task_id="task-9") == "task-9"
+    assert effective_correlation_id(explicit="", celery_task_id="task-9") == "task-9"
+
+
+def test_effective_correlation_id_generates_when_missing() -> None:
+    a = effective_correlation_id(explicit=None, celery_task_id=None)
+    b = effective_correlation_id(explicit=None, celery_task_id=None)
+    assert len(a) > 20
+    assert a != b
+
+
+def test_new_memoir_correlation_id_is_uuid_like() -> None:
+    x = new_memoir_correlation_id()
+    assert len(x) >= 32
+
+
+def test_phase2_immediate_task_id_stable_per_user_category() -> None:
+    assert _phase2_immediate_task_id("u1", "childhood") == _phase2_immediate_task_id(
+        "u1", "childhood"
+    )
+    assert _phase2_immediate_task_id("u1", "childhood") != _phase2_immediate_task_id(
+        "u2", "childhood"
+    )