Desktop installers + README for open-source launch

[tomasz-zajac-oss]

Summary

• Desktop installers. Adds electron-builder.yml and a Release Desktop App workflow. Pushing a v* tag runs type-check and tests, checks that the tag matches the package.json version, builds on all three OSes and drafts a GitHub Release with:

  • macOS dmg (arm64 + x64)
  • Windows NSIS installer
  • Linux AppImage

  PRs that touch the packaging files only build. npm run dist builds installers for the current OS.

• App name radical.studio. Used for the installers, the artifact file names (radical-studio-<version>-<os>-<arch>), the window title and the page title. radical.tools stays the family name.

• README rework:

  • hero screenshot that follows the light/dark theme, badges, and "Try in browser" / "Download" links
  • a "Why radical.tools?" section and a 4-screenshot gallery
  • install steps, including the Gatekeeper and SmartScreen workaround for unsigned builds
  • release steps and a Contributing section

• App icon. build/icon.png (512px). tools/generate-icon.js now takes --size and --out; the 128px VS Code icon is unchanged, byte for byte.

• Fix: blank window in production desktop builds. The CSP onHeadersReceived handler replaced every response header, which dropped Content-Type. Chromium then refused the renderer's module scripts, so npm start and any packaged build showed an empty window. The handler now spreads details.responseHeaders. The web build was not affected.

• electron moved to devDependencies, which electron-builder requires. This is where the large package-lock.json diff comes from.

Test plan

• npm run typecheck and npm test pass (408 tests)
• macOS: built the arm64 and x64 dmgs locally; the packaged radical.studio.app launches and renders the canvas
• Windows and Linux installers build in this PR's Release Desktop App run
• After merge: git tag v1.0.0 && git push --tags, check the draft release, publish it

The builds are unsigned for now. The workflow has a note on where to add the CSC_LINK / Apple ID secrets for signing.

🤖 Generated with Claude Code