Add Cloud Agent development environment config

[frankie-zeng]

Summary

Adds a committed Cursor Cloud Agent environment so EcuBus-Pro becomes fully usable out of the box on a fresh VM.

Changes

• .cursor/environment.json — declares the environment and its install command.
• .cursor/install.sh — idempotent bootstrap: npm install, download the pinned standalone Python (python-build-standalone) into resources/python, pip install -r resources/requirements.txt, npm run native (Linux stubs), and npm run worker:js.
• AGENTS.md — document one additional known pre-existing test failure (test/dbc/dbc.test.ts > id2001.dbc) which fails on case-sensitive Linux filesystems because the committed fixture is ID2001.dbc (same class as the already-documented s19 case mismatch).

The Cursor default base image already provides Node 22, Python 3, gcc/make, and a headless X server on display :1, so no custom Dockerfile is required.

Validation

• npm install, Python download + pip install, npm run native, and npm run worker:js all complete successfully on a fresh VM.
• npm run typecheck passes (node + web).
• Hardware-independent test smoke suite: 50 passed; the only failures are 3 pre-existing, environment-independent repo fixture bugs (documented in AGENTS.md).
• Electron GUI launches with DISPLAY=:1 npm run dev and renders end to end.