Problem

Currently gog sheets supports reading, writing, formatting, and inserting rows/columns, but there's no way to manage tabs (sheets) within a spreadsheet — you can't create, rename, or delete them.

This means users who want to set up a spreadsheet programmatically have to create tabs manually in the browser first.

Proposed Solution

Add three new subcommands:

• gog sheets add-tab <spreadsheetId> <tabName> — create a new tab
• gog sheets rename-tab <spreadsheetId> <oldName> <newName> — rename an existing tab
• gog sheets delete-tab <spreadsheetId> <tabName> — delete a tab (with --force to skip confirmation)

These use the existing Sheets batchUpdate API with AddSheetRequest, UpdateSheetPropertiesRequest, and DeleteSheetRequest.

Implementation

PR: #309

Follows the same patterns as:

• sheets insert (PR feat(sheets): add insert subcommand for rows and columns #203)
• docs tab commands (PR feat(docs): add tab support and editing commands (write, insert, delete, find-replace) #225)