Add support for OpenAI’s Codex CLI (Native or MCP)

[nkwelleepiengomejr]

Description

Add first-class integration for the OpenAI Codex CLI as a provider in Kilo.

Proposal

• MCP path (minimal): expose codex mcp in the Provider/MCP catalog.
• Native path (optional): detect codex on PATH and start a session per workspace.

Scope

• UX: surface Codex-proposed file diffs and shell commands; apply/run only after user approval.

Settings

• Model picker, autonomy level, and a zero-data-retention toggle.