feat(injects,conversations): configurable inject header, urgent inject marks the turn it cut

src/beaver_gateway/storage/models.py

@@ -163,6 +163,9 @@ class InjectQueueItem(SQLModel, table=True):
     text: str
     status: str = Field(default="queued", index=True)
     turn_id: str | None = Field(default=None)
+    interrupted_turn: bool | None = Field(default=None)
+    """An urgent inject that cut a running turn; the header tells the model
+    the ``Request interrupted`` tool result above was this, not a refusal."""
     created_at: datetime = Field(default_factory=_utcnow)
     delivered_at: datetime | None = Field(default=None)