docs: Add Cursor Cloud dev environment setup notes

[Isakdl]

Summary

Sets up the Cursor Cloud development environment for this Docusaurus documentation site and documents non-obvious run/lint caveats for future agents.

• Adds a ## Cursor Cloud specific instructions section to AGENTS.md covering how to run the dev server, the markdownlint-cli requirement for npm run lint, and why lint reports pre-existing findings.
• The environment update script installs dependencies via npm ci and adds markdownlint-cli (--no-save) so npm run lint resolves the markdownlint binary.

Environment verification

• npm ci — installs 1476 packages successfully.
• npm run lint — runs markdownlint over docs/**/*.md (exits nonzero on pre-existing content findings, expected).
• npm start — Docusaurus dev server serves the docs at http://localhost:3000/ (HTTP 200).

Walkthrough

serverpod_docs_dev_server_walkthrough.mp4

Homepage, docs navigation, and Algolia search all render correctly in the running dev server.

Homepage
Docs page
Search

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