fix(cli): handle config auth failures without traceback spam

[LarytheLord]

Summary

Fixes noisy CLI behavior in codecarbon config when an existing login token is expired/invalid.

Previously, show_config() called get_access_token() before entering its try block, so auth/refresh errors escaped and triggered a long traceback. This made the config wizard hard to use for simple re-auth flows.

This PR:

• moves API/token validation inside the guarded block in show_config()
• replaces exception re-raise with a concise warning message
• keeps the wizard flow running so users can continue local config setup

Fixes #855.

Tests

• Added test_show_config_handles_access_token_errors in tests/cli/test_cli_main.py.
• Local validation:
  • uv run pytest tests/cli/test_cli_main.py -k "show_config_handles_access_token_errors or test_api_get_calls_api_and_prints"
  • uv run ruff check codecarbon/cli/main.py tests/cli/test_cli_main.py

[SaboniAmine]

LGTM, thanks for your contribution!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.19%. Comparing base (b370a5a) to head (d9d6d50).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1080      +/-   ##
==========================================
+ Coverage   78.14%   78.19%   +0.05%     
==========================================
  Files          38       38              
  Lines        3637     3637              
==========================================
+ Hits         2842     2844       +2     
+ Misses        795      793       -2     

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