[codex] complete OKF documentation coverage

[tractorjuice]

Summary

Follow-up documentation pass for the OKF compatibility work merged in #603.

• Adds OKF import/export entries to the static guide index.
• Updates getting-started, remote-control, MCP setup, and copied dependency-matrix docs.
• Updates Codex, Copilot, OpenCode, Paperclip, Gemini, and Vibe extension documentation so OKF commands are discoverable across target formats.
• Removes brittle stale generated-command counts from extension READMEs where generated content is not tracked in this repo.

Validation

• git diff --check
• npx markdownlint-cli2 "**/*.md"