Set up Cursor Cloud dev environment (AGENTS.md)

[zinoe-1]

Summary

Sets up the ScratchV development environment for Cursor Cloud agents and documents non-obvious caveats. No product code changed.

• Adds AGENTS.md with a ## Cursor Cloud specific instructions section.
• Update script (configured via the environment tool, not committed) installs the package + optional extras + dev/test tooling:
  • pip install -e ".[all]" markdown
  • pip install pytest flake8 mypy black isort ruff types-setuptools

Verification

Ran end-to-end in the VM:

• Tests: python3 -m pytest tests/ --ignore=tests/test_simulator.py → 342 passed. (test_simulator.py has 2 pre-existing failures that CI already skips.)
• Benchmark tests: python3 -m pytest benchmarks/test_benchmark.py → 25 passed.
• Hello-world (core functionality): compiled models/graph/cnn.onnx → RISC-V RV32IM machine code and executed it in the TinyFive simulator (make bench-cnn, make bench-tinyfive).
• Full comparison + dashboard: make bench-ci (ScratchV + LLVM-IR both compile; the external-toolchain "comparison" step is expected to report failed since llc/riscv-gcc/spike are not installed).

ScratchV vs LLVM dashboard
Dynamic instruction trend

_{To show artifacts inline, enable in settings.}