feat: Plan Limit Exhaustion

[lockwobr]

There comes a time very few hours when you exhaust your plan credits. This error can get lost in the logs, and I bet happens offen for some users. Be nice if we could either get:

• A nice error message in stdout.
• Even better catch the error, parse it for when your credits reset, and print out that ralph is sleeping tell xx:yy time when the claude account is has been refreshed.

[frankbria]

This would significantly improve UX. Currently hitting rate limits results in confusing behavior buried in logs.

Proposed improvements:

1. Detect rate limit errors from Claude output
2. Parse reset time from error message
3. Display clear message: "Rate limit reached. Ralph will resume at XX:YY"
4. Either sleep until reset or exit gracefully with instructions

Related: #100 covers a specific variant of this (Extra Usage mode has different error format).