🐛 fix issue with scoping for sheets

[guimorg]

Note

Medium Risk
Moderate risk because it changes how Google auth credentials are prepared and authorized for Sheets/Drive access; incorrect scoping could break access for some credential types. Changes are covered by new unit tests for scoped vs non-scoped credentials behavior.

Overview
Fixes Google Sheets authentication by ensuring provided google-auth credentials have the required Sheets/Drive scopes before calling gspread.authorize, and emits a warning when credentials cannot be re-scoped.

Adds unit tests covering missing credentials, scoped credentials with/without Sheets scopes, and non-scoped credential warnings; includes a small test formatting tweak in BigQuery tests.

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