test(web): cover empty-draft queue flush with a keyless replay scenario

Also pin the queue-item-not-found convergence arm through the hub and
document the repeated-trigger contract on steerQueue.

apps/web/tests/snapshots/steer-all/settled.expected.md

@@ -0,0 +1,51 @@
+- banner:
+  - navigation "Session hierarchy":
+    - button "Use the ask_user_question tool to" [disabled]
+  - tablist:
+    - tab "Chat" [selected]
+    - tab "Trajectory"
+- text: Use the ask_user_question tool to ask me exactly one question with id "checkpoint", question "Ready to continue?", header "Checkpoint", and options labeled "Yes" and "No". After I answer, reply with one short sentence acknowledging my answer and stop. {{clock}}
+- button "Copy":
+  - img
+- button "Branch into a new conversation" [disabled]:
+  - img
+- text: Available only on the last message of a completed turn
+- button "Context injection @deepseek-ai/dsh-system-prompt":
+  - img
+  - img
+  - text: Context injection @deepseek-ai/dsh-system-prompt
+- button "Think The user wants me to ask them a checkpoint question first, then continue with whatever they interject. Let me do exactly that.":
+  - img
+  - img
+  - text: Think The user wants me to ask them a checkpoint question first, then continue with whatever they interject. Let me do exactly that.
+- button "Ask question 1/1 answered":
+  - img
+  - img
+  - text: Ask question 1/1 answered
+- text: "Interjection Interjection: include the word BANANA in your final reply. {{clock}}"
+- button "Copy":
+  - img
+- button "Branch into a new conversation" [disabled]:
+  - img
+- text: "Available only on the last message of a completed turn Interjection Interjection: include the word ORANGE in your final reply. {{clock}}"
+- button "Copy":
+  - img
+- button "Branch into a new conversation" [disabled]:
+  - img
+- text: Available only on the last message of a completed turn
+- paragraph: "Got it: BANANA and ORANGE."
+- button "Copy":
+  - img
+- button "Branch into a new conversation":
+  - img
+- text: {{clock}} Ran for {{duration}} TTFT {{duration}} {{throughput}} tok/s
+- textbox "Message the agent"
+- button "Commands":
+  - img
+- 'button "Access mode, current: Workspace Write"': Workspace Write
+- button "Select model, current DeepSeek-V4-Flash":
+  - text: DeepSeek-V4-Flash
+  - img
+- button "0% of context used"
+- button "Send message" [disabled]
+- text: 1 turns · 2 steps LLM {{duration}} · Tool call {{duration}} TTFT avg {{duration}} · {{throughput}} tok/s Cache hit 0% Input 20 tok · Output 20 tok