feat: add Safari Web Extension support

[coryboyle]

Summary

Add Safari Web Extension support for macOS, enabling Spector.js WebGL debugging in Safari.

Architecture

The Safari extension lives in safari-extension/ (separate from the Chrome/Firefox extensions/ directory) because Safari requires a fundamentally different approach to MAIN-world code execution.

Key design decisions

• browser.scripting.registerContentScripts() with world: "MAIN" — Safari doesn't support manifest-declared MAIN-world content scripts. The scripting API registers pageScript.js as a MAIN-world content script at runtime, which bypasses page CSP and runs at document_start.
• browser.scripting.executeScript() — Injects the Spector bundle and initialization code into the page's MAIN world on demand (when the user enables Spector), also bypassing CSP.
• Single ISOLATED-world content script — contentScript.js handles all browser.runtime messaging and bridges to the MAIN world via CustomEvents and shared DOM elements.
• Defensive getContext patch — Uses Function.prototype.apply() for argument forwarding and wraps all extension logic in try-catch to ensure extension errors never break page WebGL functionality.

Files

File	Purpose
safari-extension/manifest.json	MV3 manifest with scripting permission
safari-extension/pageScript.js	MAIN-world getContext() interception (registered via scripting API)
safari-extension/pageScriptInit.js	MAIN-world Spector init (injected via scripting API)
safari-extension/contentScript.js	ISOLATED-world messaging bridge
safari-extension/background.js	Service worker: registers content scripts, handles bundle injection
safari-extension/popup.html/js	Extension popup UI
safari-extension/result.html/js	Capture result viewer
documentation/safari-extension.md	Build, dev, and distribution docs

Build & Test

npm run build                    # Builds bundle + copies to safari-extension/
xcrun safari-web-extension-converter safari-extension/ \
  --project-location safari-xcode \
  --app-name "Spector.js" \
  --bundle-identifier com.babylonjs.spectorjs \
  --macos-only

Then open the Xcode project, build & run, and enable the extension in Safari.

Also included

• CI job on macOS runner to validate the Safari extension build
• Updated README with Safari in the browser extension list

[sebavan]

it looks like a lot of code in the safari-extension folder is a dupplicate and this might make maintenance harder.

Any way to share any shareable thing ?