feat: add MiniMax Messages provider support

[octo-patch]

Summary

• Add a dedicated MiniMax Messages provider with global and China Base URL support.
• Register MiniMax-M3 and MiniMax-M2.7 with verified context, modality, thinking, and pricing metadata.
• Cover authentication, routing, request paths, persistence, documentation, and generated provider facts.

Testing

• cargo fmt --all
• cargo check -p codewhale-config -p codewhale-agent -p codewhale-tui -p codewhale-cli --all-targets --locked
• cargo test -p codewhale-config --locked minimax -- --nocapture
• cargo test -p codewhale-config --locked bundled_asset -- --nocapture
• cargo test -p codewhale-agent --locked minimax -- --nocapture
• cargo test -p codewhale-tui --bin codewhale-tui --locked minimax -- --nocapture
• cargo test -p codewhale-cli --locked parses_auth_subcommand_matrix -- --nocapture
• node web/scripts/check-facts.mjs

Checklist

• Updated docs or comments as needed
• Added or updated tests where relevant
• Verified TUI behavior manually

[github-actions]

Thanks @octo-patch for taking the time to contribute.

This repository is observing a maintainer-managed PR intake gate in dry-run mode, so this pull request is staying open. This note helps maintainers prepare the allowlist before any enforcement is considered.

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