say which shells nobody is looking at

The sidecar has always sent `clients` on each session and this list has always dropped it, so a shell
you are typing into and a shell nothing is attached to rendered identically. It is now on the type,
shown as "N attached", and a zero earns the row an orphan badge — the count only helps if you do not
have to read it to notice.

Also records §5.1 and the whole of §1 in the todo, including that the diff-the-layout implementation
§5.1 used to propose is struck and why.

src/workspaces/officerdev/src/apps/Terminal/RunningShells.tsx

@@ -22,6 +22,10 @@ type PtySession = {
   lastActivityAt: number;
   title?: string;
   pid?: number;
+  // How many sockets are attached. The sidecar has always sent it and this list has always dropped it,
+  // which left every row looking the same — yet it is the only field that says whether a shell is one
+  // you are looking at or one nothing is pointing at any more.
+  clients?: number;
 };
 
 const RELATIVE_UNITS: [limit: number, div: number, unit: string][] = [
@@ -87,10 +91,19 @@ export const RunningShells = () => {
             <div className="min-w-0 flex-1">
               {/* The title the shell set for itself (OSC 0/2) — usually the running command. It is what
                   makes an abandoned shell identifiable instead of a bare uuid. */}
-              <p className="truncate text-xs font-medium">{s.title || 'shell'}</p>
+              <p className="truncate text-xs font-medium">
+                {s.title || 'shell'}
+                {s.clients === 0 && (
+                  <span className="ml-1.5 rounded bg-amber-500/15 px-1 py-px text-[10px] text-amber-400">
+                    orphan
+                  </span>
+                )}
+              </p>
               <p className="truncate font-mono text-[10px] opacity-50">
                 {s.sessionId.slice(0, 8)} · {s.cols}×{s.rows}
-                {s.pid ? ` · pid ${s.pid}` : ''} · idle {since(s.lastActivityAt)} · up {since(s.createdAt)}
+                {s.pid ? ` · pid ${s.pid}` : ''}
+                {s.clients === undefined ? '' : ` · ${s.clients} attached`} · idle {since(s.lastActivityAt)} · up{' '}
+                {since(s.createdAt)}
               </p>
             </div>
             <button