Set up Cursor Cloud dev environment

[burtenshaw]

Summary

Sets up the development environment for the OpenEnv monorepo and documents cloud-specific setup for future agents.

• Adds AGENTS.md with a ## Cursor Cloud specific instructions section covering project shape, dependency refresh, lint/test commands, how to run an environment server end-to-end, and the optional Gradio web-UI gotcha.
• Configures the startup update script to install uv (if missing) and run uv sync --all-extras.

No application code was modified.

Environment verification

• uv sync --all-extras installs core + CLI + provider extras into .venv/.
• Lint: ruff format --check and ruff check pass; usort check flags two pre-existing files only.
• Tests: PYTHONPATH=src:envs uv run pytest tests/ -q → 1379 passed, 129 skipped (optional env deps).
• Ran the echo_env reference server and completed a hello-world client flow (reset → list_tools → step(echo_message)), echoing back the input message.

Hello-world client log:
echo_hello_world.log