chore: rewrite README for clarity and conversion

[xb3sox]

Summary

• Rewrite README with problem-first hook, quick start order fix, and example status output
• List all MCP-only agents by name; add before/after framing and Windows PATH step
• Tighten copy (caveman mode): short sentences, scannable sections, same technical accuracy

Test plan

• Docs-only change; no code behavior affected
• Verified agent tiers match src/agents/artifacts.rs
• Verified CLI commands match Clap definitions

Checklist

• PR targets main
• Commit messages follow Conventional Commits
• CHANGELOG.md updated (for user-facing changes) — skipped; README-only polish

Made with Cursor