feat(setup): Yes-default + session-persist on claude-assist, quieter first-chat

Three UX tweaks after watching a user walk through setup:

1. Claude-assist "Run this command?" now defaults to Yes. After Claude has already been asked to diagnose + explained the fix, the vast majority of users want to run it — the No-default added friction without proportional safety.

2. claude-assist persists its session across failures in one setup run. First invocation captures session_id from the stream-json init event; subsequent invocations pass --resume <id>. Claude sees prior failures as conversation history instead of treating each hiccup as a blank-slate ticket.

3. First-chat flow no longer drops the user into a free-text chat loop by default. Instead: explain what the ping/pong check is doing, wait for the pong, then offer "Continue with setup" (recommended, default) or "Pause here and chat with your agent from the terminal" (opt-in). The free-text loop is still reachable, just not the default path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

setup/auto.ts

@@ -246,10 +246,33 @@ async function main(): Promise<void> {
       );
     }
     if (!skip.has('first-chat')) {
+      p.log.message(
+        dimWrap(
+          "Your assistant runs in an isolated sandbox. I'm going to send it a quick test message (ping) and wait for a reply (pong) to confirm it's responding. First startup typically takes 30–60 seconds while the sandbox warms up.",
+          4,
+        ),
+      );
       const ping = await confirmAssistantResponds();
       if (ping === 'ok') {
         phEmit('first_chat_ready');
-        await runFirstChat();
+        const next = ensureAnswer(
+          await p.select({
+            message: 'What next?',
+            options: [
+              {
+                value: 'continue',
+                label: 'Continue with setup',
+                hint: 'recommended',
+              },
+              {
+                value: 'chat',
+                label: 'Pause here and chat with your agent from the terminal',
+              },
+            ],
+          }),
+        ) as 'continue' | 'chat';
+        setupLog.userInput('first_chat_choice', next);
+        if (next === 'chat') await runFirstChat();
       } else {
         phEmit('first_chat_failed', { reason: ping });
         renderPingFailureNote(ping);