fix: complete rclone OAuth configuration

[CruxExperts]

Summary

• Lazily load Google Drive management support inside auth-gdrive so ordinary bbman startup and dependency checks do not require the management package to import eagerly.
• Handle rclone's capitalized ConfigOut RC response fields and reject actual Option/Error responses without leaking secrets.
• Continue state-only rclone config transitions using continue, state, and result, bounded to 32 continuation calls.
• Add regression coverage for lazy imports, redaction, pending questions, and the exact continuation boundary.

Verification

• Full suite: 620 passed.
• Ruff, py_compile, generated CLI metadata, version sync, publishing readiness, and diff checks passed.
• Real local rclone RC core/version smoke passed.
• Independent follow-up review: no material findings.
• No credentials or tokens committed.

This follows merged PR #15 and addresses its automated review findings.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Auto-answer Drive's shared-drive prompt

When configuring a normal My Drive remote with no team_drive, rclone's Drive post-config path asks the config_change_team_drive question after OAuth; its config protocol also requires any default config answers to be passed again on each --continue (see https://rclone.org/commands/rclone_config_create/#synopsis). Since this handler now rejects every returned Option, bbman auth-gdrive can complete the browser OAuth and then fail instead of accepting the default “no shared drive” answer. Add config_change_team_drive=false to the default parameters (and preserve it across continuations) before treating remaining options as unsupported.

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