MCP: add resume-path support for Codex sessions

[rabsef-bicrym]

Summary

• Add resume_path to the Codex MCP tool schema + implementation
• Cover the schema update in tests
• Run rustfmt

Context

Happy CLI can resume Codex sessions by passing a resume path through MCP. This enables a smooth “pick up where you left off” flow across desktop + mobile. The intent is to make Codex feel first‑class in Happy, approaching parity with other CLI workflows (e.g., Claude Code), without altering the existing Codex CLI UX.

Implementation notes

• MCP schema and tool wiring accept an explicit resume path
• Tests updated to match the new schema

Testing

• python scripts/asciicheck.py
• python scripts/readme_toc.py
• python scripts/format.py
• python scripts/stage_npm_packages.py
• cargo fmt --all
• cargo clippy --all-targets --all-features
• cargo shear
• cargo check --all-targets --all-features
• cargo nextest run --all-targets --all-features
• cargo deny check
• pnpm --filter @openai/codex-sdk lint
• pnpm --filter @openai/codex-sdk test -- --runInBand
• pnpm --filter @openai/codex-sdk build
• pnpm --filter @openai/codex-cli shell-tool-mcp:format
• pnpm --filter @openai/codex-cli shell-tool-mcp:test
• pnpm --filter @openai/codex-cli shell-tool-mcp:build

Companion PR

• Codex: resume via MCP and improve local/remote switching slopus/happy-cli#151

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