Add a devenv setup and switch to pnpm

[raszi]

This change adds a devenv setup with git hooks. It also switches the project from npm to pnpm and upgrades Prettier to version 3.

Changes

• Add a devenv setup. The dev shell installs Node.js and pnpm. If you use direnv, .envrc loads the dev shell.
• Add git hooks: eslint, tsc, prettier, editorconfig-checker, typos, ripsecrets, actionlint, check-json, check-yaml, check-merge-conflicts, nixfmt and deadnix. The JavaScript hooks use the tools from node_modules, so the hooks and CI use the same versions.
• Add .editorconfig. It sets the line length to 120. Prettier reads the line length from this file.
• Upgrade Prettier to version 3. Prettier 2 followed the links in .devenv into the Nix store, so pnpm run format did not stop. The format function of the tool is now async.
• Format the code with Prettier.
• Remove the old .eslintrc.json. It loaded the Raycast ESLint config, and ESLint 10 does not use it.
• Switch from npm to pnpm. The lock file keeps the same package versions. CI installs pnpm with pnpm/action-setup.

Usage

devenv shell
pnpm install
pnpm add --global "$PWD"