Add development environment setup (AGENTS.md)

[q1]

Summary

Adds AGENTS.md with Cursor Cloud-specific development environment instructions for the Cookie Quick Manager Firefox WebExtension.

What's included

• AGENTS.md with:
  • Key tools needed (web-ext, Firefox)
  • Common commands table (lint, build, run, clean)
  • Environment gotchas (symlink setup, Firefox snap vs APT, expected lint warnings, vendored JS libraries)

Development environment setup

The following was verified as working:

• Lint: make lint — passes with 0 errors (expected warnings/notices only)
• Build: make build — produces dist/cookie_quick_manager-0.5rc2.zip
• Run: web-ext run --source-dir=src --firefox=firefox --no-reload — extension loads and is fully functional in Firefox

Update script (VM startup)

npm install -g web-ext
sudo mkdir -p /node_modules/.bin
sudo ln -sf $(which web-ext) /node_modules/.bin/web-ext