feat(irc): work-aware peer roster with role and activity

Add a display-only `activity` field to AgentRef plus `setActivity`, fed
from the subagent progress chokepoint with a short gist of the agent's
latest intent (or current tool). Render it in the `irc list` output, the
subagent peer roster, and the TUI peer card, beside the role-derived
display name. setActivity emits no event — the roster reads on demand —
so the per-tool-call rate stays off the registry listener path. Peers
with no activity render without a dangling clause.

Refs #2470

Op: extend

packages/coding-agent/src/task/executor.ts

@@ -125,7 +125,10 @@ function renderIrcPeerRoster(selfId: string): string {
 		.list()
 		.filter(ref => ref.id !== selfId && ref.status !== "aborted");
 	if (peers.length === 0) return "- (no other agents)";
-	const lines = peers.map(peer => `- \`${peer.id}\` — ${peer.displayName} (${peer.kind}, ${peer.status})`);
+	const lines = peers.map(
+		peer =>
+			`- \`${peer.id}\` — ${peer.displayName} (${peer.kind}, ${peer.status})${peer.activity ? `: ${peer.activity}` : ""}`,
+	);
 	if (peers.some(peer => peer.status === "idle" || peer.status === "parked")) {
 		lines.push("Idle/parked peers are not gone: messaging them wakes (or revives) them.");
 	}
@@ -841,6 +844,9 @@ function createSubagentRunMonitor(args: RunMonitorArgs): SubagentRunMonitor {
 	const emitProgressNow = () => {
 		progress.durationMs = Date.now() - startTime;
 		onProgress?.({ ...progress });
+		const activityGist =
+			progress.lastIntent ?? (progress.currentTool ? `running ${progress.currentTool}` : undefined);
+		if (activityGist) AgentRegistry.global().setActivity(id, activityGist);
 		if (args.eventBus) {
 			args.eventBus.emit(TASK_SUBAGENT_PROGRESS_CHANNEL, {
 				index,