feat(tui): offer r to resume a session whose pane has died

Refusing the attach stopped the freeze but told the user to throw the session
away (`x` to close, `n` for new), which loses the conversation. tmux's own
dead-pane screen already says what to do instead: `claude --resume "<name>"`.

The Error card now offers `r` when the row can actually be resumed (claude,
with a conversation id and a working directory), and the footer says so. One
press resumes into a fresh pane and attaches to it, so a dead end becomes
recovery.

⚠️ Three things keep this from becoming the resume runaway that once spawned 35
sessions in 40 seconds. The offer holds a session ID, not a row, and is
re-resolved from the model when the key is pressed: a row captured when the
card opened is stale by then. It disarms BEFORE anything async, so a second `r`
cannot start a second resume. And it routes through resumeSelected(), which
owns the `resuming` flag and ends in attachToSession() rather than the group
dispatch.

⚠️ The `r` branch has to run BEFORE the generic dismiss, because a message
overlay is dismissed by ANY key: without that ordering the offer is consumed as
"some key was pressed" and the card merely closes. `help` keeps the any-key
behaviour, so the two modes no longer share a case.

Verified end to end against a genuinely dead claude pane: card, footer, one
press, one new session, and F12 back to the dashboard.

test/tui/tui-app.test.ts

@@ -460,6 +460,16 @@ describe('buildListLines', () => {
   });
 });
 
+describe('the dead-row resume offer', () => {
+  it('advertises r on the message footer only while an offer is armed', () => {
+    const base = { server: true } as const;
+    expect(footerKeysFor('message', GLYPHS, { ...base, resumeOffer: true })).toEqual(['r resume', 'esc dismiss']);
+    // Without an offer the card is a plain notice, and a footer promising `r`
+    // would be advertising a key that does nothing.
+    expect(footerKeysFor('message', GLYPHS, base)).toEqual(['esc dismiss']);
+  });
+});
+
 describe('the one-key way out', () => {
   it('names a single key with no modifier at all', () => {
     // The whole point: three beta rounds died on a chord that had to be typed