chore: ignore local Codex MCP credentials

[StudentWeis]

Motivation

Ropy's project-local Codex MCP configuration contains AgentBay credentials for cross-platform GUI testing. The local configuration must not be committed to the repository.

Proposed Solution

Ignore /.codex/config.toml so developers can configure project-scoped MCP servers without exposing credentials.

Alternatives Considered

• Use the global Codex configuration: rejected because the MCP servers should apply only to ropy.
• Leave the file unignored: rejected because it risks accidental credential disclosure.

Acceptance Criteria

• /.codex/config.toml is ignored by Git.
• Existing tracked files are unaffected.
• The local project configuration remains available to Codex from the ropy workspace.

Scope

• In scope: Git ignore rule for the local Codex MCP configuration.
• Out of scope: committing any MCP URL or API key.