docs: Cursor Cloud dev environment setup instructions

[maxiguillermo1]

Summary

Adds a Cursor Cloud specific instructions section to docs/AGENTS.md documenting how to develop and verify Kairo in cloud agent VMs.

What was verified in the cloud VM

• npm ci — dependencies install cleanly
• npm run validate — typecheck, lint, and 294 Jest tests pass
• npm run start — Metro dev server on port 8081 (packager-status:running)
• npm run export:ios-check — iOS bundle export succeeds (1678 modules)
• Mood persistence smoke: npm test -- --testNamePattern="upsert and delete single rows"

Notes for future agents

• Cloud VMs have no iOS/Android simulators; use Metro + bundle export + Jest for automated verification
• npm run web is secondary and may fail on expo-sqlite WASM in minimal cloud setups
• VM startup update script: npm ci

Demo

kairo-dev-env-demo.mp4

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