Add Cursor Cloud specific instructions to AGENTS.md

[ramonverse]

Summary

Adds Cloud Agent-specific development environment instructions to AGENTS.md so future agents can efficiently set up and operate in this codebase.

What's added

• Service startup order: Docker daemon -> PostgreSQL -> DB migrate/seed -> Dev server
• Docker-in-Docker gotchas: fuse-overlayfs storage driver and iptables-legacy requirements for Firecracker VM
• Environment config: Default .env.local setup, Turnstile test keys, optional AI provider keys
• Key commands table: Quick reference for install, lint, build, dev, DB operations
• Gotchas: Bun PATH, non-standard Postgres port (5437), no automated test suite

Demo

openlingo_dev_environment_demo.mp4
Full dev environment setup: sign-up, onboarding, and browsing units.

Landing page
Main dashboard with AI Tutor
Browse public units and courses

Verification

• bun install - dependencies install successfully
• bun run lint - ESLint runs (pre-existing warnings)
• bun run build - production build succeeds
• bun run dev - dev server starts on port 3000
• Sign-up, onboarding, and unit browsing all work end-to-end

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