feat(feedback): disclose session sharing in the /feedback acknowledgement

The /feedback acknowledgement now echoes the receiving session id and
reports the mounted telemetry backend's sharing policy: the telemetry seam
exposes a backend-independent TelemetrySharingStatus through a required
abstract sharing member on the Telemetry service, the OTel backend maps its
mode onto it, and the command appends one policy-only sharing sentence
(full / feedback-only / disabled / not configured) to the acknowledgement.
The web client renders the text through the existing command row without a
client change; a new assembled-browser e2e mounts the shipped telemetry row
in FULL mode against a local dead endpoint and pins the shipped default
sentence as a keyless golden.

apps/web/tests/snapshots/feedback-command/ack.expected.md

@@ -0,0 +1,35 @@
+- banner:
+  - navigation "Session hierarchy":
+    - button "Reply with the single word" [disabled]
+  - tablist:
+    - tab "Chat" [selected]
+    - tab "Trajectory"
+- text: Reply with the single word LIGHTHOUSE and stop. {{clock}}
+- button "Copy":
+  - img
+- 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 reply with a single word. Let me comply.":
+  - img
+  - img
+  - text: Think The user wants me to reply with a single word. Let me comply.
+- paragraph: LIGHTHOUSE
+- button "Copy":
+  - img
+- button "Branch into a new conversation":
+  - img
+- text: {{clock}} Ran for {{duration}} TTFT {{duration}} {{throughput}} tok/s
+- img
+- text: feedback Feedback recorded for session session-{{uuid}}. Session sharing is enabled.
+- 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 "6% of context used"
+- button "Send message" [disabled]
+- text: 1 turns · 1 steps LLM {{duration}} TTFT avg {{duration}} · {{throughput}} tok/s Cache hit 99% Input 7.8K tok · Output 21 tok