feat: expose full rate limit headers on RateLimitError

[0xneobyte]

Problem

The backend returns the following headers on 429 responses:

• X-RateLimit-Limit-PerMinute
• X-RateLimit-Remaining-PerMinute
• X-RateLimit-Limit-PerDay
• X-RateLimit-Remaining-PerDay
• Retry-After

The SDK currently only parses Retry-After and discards the rest. Callers have no way to know which limit was hit or what the limit value is, making it impossible to implement informed backoff or meaningful error messages.

Proposed Behaviour

Parse all rate limit response headers and expose them as fields on RateLimitError.

} catch (e) {
  if (e instanceof RateLimitError) {
    console.log(e.retryAfter)      // seconds to wait
    console.log(e.limitPerMinute)  // per-minute cap, or undefined
    console.log(e.limitPerDay)     // per-day cap, or undefined
  }
}

Files to Modify

File	Change
src/errors.ts	Add limitPerMinute, limitPerDay fields to RateLimitError
src/client.ts	Parse additional headers in handleErrorResponse

Acceptance Criteria

• RateLimitError.retryAfter behaviour is unchanged
• RateLimitError.limitPerMinute set when header is present
• RateLimitError.limitPerDay set when header is present
• Fields are undefined when the corresponding header is absent
• Tests cover both per-minute and per-day header scenarios