fix password fields not clearing after validation error

When pasting an invalid token, the old value stayed in the input
field. Pasting a new token appended to the old one instead of
replacing it, causing repeated validation failures.

Add clearOnError: true to all 8 password prompts across setup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

setup/auto.ts

@@ -706,6 +706,7 @@ async function runPasteAuth(method: 'oauth' | 'api'): Promise<void> {
   const answer = ensureAnswer(
     await p.password({
       message: `Paste your ${label}`,
+      clearOnError: true,
       validate: (v) => {
         if (!v || !v.trim()) return 'Required';
         if (!v.trim().startsWith(prefix)) {