M1：镜生域后端闭环——灵胚/照心试演/启镜原子闸门/执镜关系/命台租约/魂籍签名导出/死亡冷静期（迁移 001，测试 7 用例）

backend/app/models/runtime.py

@@ -14,11 +14,18 @@ class Run(Base):
     __tablename__ = "runs"
 
     id: Mapped[str] = mapped_column(String(80), primary_key=True, default=new_run_id)
-    character_id: Mapped[str] = mapped_column(String(80), ForeignKey("characters.id"), index=True)
+    # rewrite/1.0：照心试演（kind=rehearsal）无正式人物，character_id 允许为空
+    character_id: Mapped[str | None] = mapped_column(
+        String(80), ForeignKey("characters.id"), index=True, nullable=True
+    )
     session_id: Mapped[str | None] = mapped_column(
         String(80), ForeignKey("chat_sessions.id"), index=True
     )
     status: Mapped[str] = mapped_column(String(40), nullable=False, default="queued", index=True)
+    # run.kind：foreground / background_task / awakening / rehearsal（契约词典 §8.2）
+    kind: Mapped[str] = mapped_column(
+        String(40), nullable=False, default="foreground", server_default="foreground"
+    )
     goal: Mapped[str | None] = mapped_column(String(300))
     origin: Mapped[str] = mapped_column(String(40), nullable=False, default="chat")
     model_hint: Mapped[str | None] = mapped_column(String(120))