Add 1Password-backed auth vault profiles

[Stanzilla]

Summary

• add 1Password-backed auth vault profiles with a recommended item-based flow via the onepassword-item and onepassword-vault flags
• resolve username, password, and optional OTP values locally at auth login time through the 1Password CLI
• keep username-op, password-op, and otp-op as advanced fallbacks for partial or custom 1Password setups and second factors handled outside 1Password such as SMS or email
• update CLI help, docs, skills, and tests to cover the new auth flow

Testing

• cargo fmt -- --check
• cargo test -q
• cargo clippy -q

Closes #711.

[vercel]

@Stanzilla is attempting to deploy a commit to the Vercel Labs Team on Vercel.

A member of the Team first needs to authorize it.

[Stanzilla]

@ctate what do you think? this idea still worth exploring? It's been a while and I'd love to know if I should keep the PR up-to-date or not :)

[Stanzilla]

@ctate Another way would be to adopt https://www.1password.dev/sdks - what do you prefer?

[Stanzilla]

@ctate Another way would be to adopt 1password.dev/sdks - what do you prefer?

ah nvm, they don't have a Rust version...