chore: v2.8.12 — clone queue and progress, session defaults, chat agents, drops as @ mentions

Whole tree from parallel sessions, plus the version bump:
- Clone: a queue with live progress (Add workspace and extra folders),
  clones run under nice/ionice so the machine stays responsive.
- Settings → AI tools → Session defaults: a new session's default
  permission mode / bypass per account.
- Chat lists the background subagents that have not reported back yet.
- A file pasted or dropped into a claude pane goes in as an @ mention.
- Changes panel: say why amend/undo is refused on a pushed commit.
- openapi.yaml regenerated (Artifacts, Host, resumeById).

client/src/components/conversation/ConversationView.tsx

@@ -17,7 +17,9 @@
  * A caller that knows the session has ended passes `ended`: nothing more is
  * being written, so the catch-up poll drops from 3 s to 60 s and the
  * sub-agent list stops being rescanned — a `new_event` frame, a reconnect or
- * the view being shown again still fetch the tail at once.
+ * the view being shown again still fetch the tail at once. The main
+ * transcript hands MessageList its `sessionId`, so the list can read its
+ * background agents' own transcripts for their progress.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 /* =============================================================================
@@ -622,6 +624,9 @@ function ConversationViewPane({
               waiting={waiting}
               onOpenTerminal={onOpenTerminal}
               stopped={stopped}
+              sessionId={
+                selectedTranscript && selectedTranscript !== "main" ? undefined : sessionId
+              }
             />
           )}
         </div>