Create and install custom Codex agent roles with guided configuration and validation.

• Collects required inputs (model, reasoning effort, developer instructions, role name, install scope) before writing any files, with strict validation against the config schema
• Writes minimal role config files by default, adding optional parameters like sandboxing, web search controls, and MCP servers only when explicitly requested
• Installs roles into global (~/.codex/config.toml) or project-scoped (.codex/config.toml) config with automatic backups and additive safety
• Validates role declarations and config file keys against codex-rs/core/config.schema.json before reporting success
• Provides runnable spawn examples and clear output showing what was configured versus what remains available to inherit