* docs: refresh README with badges, MCP cross-link, CI example, client count
- Add npm and MCP-server badges at the top
- Add "Prefer AI?" callout pointing to @emailens/mcp
- Correct supported-clients count from 12 to 15 (engine has shipped 15
since @emailens/engine 0.9.0 added Outlook iOS / Outlook Android)
- Add "CI / GitHub Actions" subsection under the lint command with a
copy-paste workflow yaml using `emailens lint --fail-on-warning`
- Cross-link to the Marketplace Action for richer reports
* chore(release): 0.3.4 — bump version and fix stale client count in description