feat(cli): add support command; improve Postman request titles and docs sync

[Statsly-org]

Summary

• Add pman support CLI command that prints the Discord invite (https://discord.gg/4FBYAMxwdk) and show it in pman help
• Improve Postman request naming: prefer schema['x-pman-name'] / schema['x-name'] (emitted to OpenAPI by @fastify/swagger) instead of long summary strings
• Generate request documentation with summary as the first paragraph, plus auto-generated route metadata
• Write docs to the fields Postman actually uses in Collection v2.1: item.request.description (and item.description for compatibility)
• Update README + playground example + tests

Why

• OpenAPI summary is often too long to be a good Postman request title
• @fastify/swagger does not emit plain schema.name into OpenAPI; OpenAPI x-… extensions work reliably
• Postman’s “Docs” view for requests is backed by the request description, not just the top-level item description

Test plan

• npm run lint
• npm test
• npm run build && node examples/playground.mjs (verify Postman shows short titles + filled Docs)

Notes

• Suggested next manual check in Postman Desktop: open a request and confirm Name, Description/Docs, and that baseUrl still works

Checklist

• No secrets committed
• User-facing text is English (README)

Closes #6