Enhance AxmeAuthError messages for status codes 401 and 403

[vivan070707-ctrl]

This PR improves error messages for authentication failures.

• 401: Invalid API key (clear message added)
• 403: Access denied (permission issue clarified)

This improves developer experience by providing more meaningful feedback.

[George-iam]

Good direction! A couple of things to adjust:

1. Don't replace the server message entirely - the server may return useful details like "API key expired" or "actor_token required for this route". Instead, prepend the user-friendly hint:

   message = f"API key invalid - check AXME_API_KEY or run `axme login`. Server: {message}"

2. Keep the original message as fallback context so users can debug.

3. Add a test case in tests/test_client.py - mock a 401 response and verify the exception message contains both the hint and server detail.

[vivan070707-ctrl]

I have updated it again you want any further changes ples tell
Thank you