Windows: add console OAuth fallback when local server ports are blocked

[Foadsf]

On Windows systems where ports 8080–8099 are blocked (e.g. by firewall, AV, or Docker Desktop), GYB’s OAuth flow fails with WinError 10013 because _wait_for_http_client cannot bind a local HTTP listener. This prevents any authentication from succeeding.

This patch implements a robust fallback:

• _wait_for_http_client:

  • Wrapped in try/except, signals d['error'] = 'local_server_failed' instead of crashing when no port can be bound.
  • Leaves the original local server flow unchanged when ports are free.

• ShortURLFlow:

  • Added __init__ to capture and persist OAuth scopes in self._gyb_scopes.
  • Enhanced run_dual to detect local_server_failed and transparently switch to a manual console flow:
    • Generates an authorization URL with http://localhost redirect.
    • Opens browser if possible. - Prompts user to paste either the full redirect URL or just the code value. - Exchanges the code with self.fetch_token() and returns credentials.

Key design decisions:

• Reuse the existing flow object (self) to maintain state consistency.
• Avoid passing redirect_uri again to fetch_token() to prevent conflicts.
• Accept both full redirect URLs and raw codes for user convenience.
• Added docstrings and commented debug logging for future diagnosis.

This resolves authentication failures on Windows while preserving backward compatibility on platforms where the local server works.

Fixes: #370

Tested:

• --action estimate, --action count, and --action print-labels complete successfully with cached oauth2.txt after console flow.

[Foadsf]

Pushed a fix for the UnboundLocalError caused by local variable shadowing of urlparse. Verified working on Windows.

[Foadsf]

Updated PR with fix for httplib2 certificate environment variable in Miniconda setups