swarm-ui: a maximize button on each pane of a terminal group opens that agent's own terminal

docs/swarm/ui.md

@@ -166,7 +166,8 @@ a group of the two, with its own header tab at `/agents/group/<id>`. In a group,
 the same drag onto a pane splits that pane, as many times as you like, and
 dragging a pane's header badge onto another pane moves it there. The **split**
 button in a pane's header does the same for an agent whose terminal tab is open:
-**right** or **below** puts it beside the pane. The **×** takes the pane's
+**right** or **below** puts it beside the pane. **maximize** opens that
+agent's own terminal in its tab, or goes to the tab when one is open already. The **×** takes the pane's
 agent out of the group, and a group left with one agent goes, landing on that
 agent's own terminal. Drag a divider to resize, or focus it and use the arrow
 keys. Panes have no minimum size; a divider stops at 2% so a pane can't

frontend/packages/swarm-ui/src/pages/agents/AgentGroupPage.tsx

@@ -10,6 +10,7 @@
 import { useEffect } from "preact/hooks";
 import { useLocation, type RouteComponentProps } from "wouter-preact";
 import { Badge } from "@hive/shared/badge.js";
+import { ExpandIcon } from "@hive/shared/icons.js";
 import { AgentIcon } from "../../agent/AgentIcon.js";
 import {
   AgentTermPreview,
@@ -158,6 +159,14 @@ export function AgentGroupPage({
                   groups.update(id, (r) => splitPane(r, agent, other, side))
                 }
               />
+              <Badge
+                icon={<ExpandIcon />}
+                value="maximize"
+                title={`open ${agent}'s terminal on its own`}
+                onClick={() =>
+                  open({ href: termPaths(agent).page, label: agent })
+                }
+              />
               <Badge
                 variant="quiet"
                 value="×"