fix: retry 500 errors, detect serverError in 200 responses, session reuse

[benkwok1983-cmd]

Fix for #7 - 500 Server Error

Changes:

• **
  equests.Session()** - persists cookies across requests, reduces captcha triggers
• 500 error retry - exponential backoff, up to 3 retries
• serverError detection - catches errors in HTTP 200 responses with serverError field
• Captcha detection - detects hCaptcha/CF challenges, prompts for manual token (no paid API needed)
• 30s timeout - prevents hanging requests

/claim #7

[opirebot]

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