OAuth token not persisted/refreshed for --print mode, breaks automation

Bug Description

When using claude --print in automation (e.g., Paperclip AI agent orchestration), the OAuth token expires after approximately 8 hours. After expiry:

1. The .credentials.json file gets wiped (all fields become null/empty strings)
2. claude --print returns "Not logged in · Please run /login"
3. There is no refreshToken stored, so automatic refresh is impossible
4. An interactive claude session started before expiry continues to work (in-memory token), but any NEW process fails

Expected Behavior

• OAuth refresh token should be stored in .credentials.json
• Token should auto-refresh using the refresh token when it expires
• OR: provide a claude auth refresh command for automation use cases

Environment

• Claude Code v2.1.81
• Windows 11
• Auth type: claudeAiOauth
• Usage: Paperclip AI spawns claude --print --dangerously-skip-permissions as agent workers

Impact

This makes 24/7 autonomous operation impossible. Every ~8 hours, all automation stops and requires manual /login intervention.

Reproduction Steps

1. Run claude and /login to authenticate
2. Use claude --print -p "echo ok" - works
3. Wait ~8 hours for token to expire
4. claude --print -p "echo ok" → "Not logged in"
5. Check ~/.claude/.credentials.json → all fields are null/empty