Add Firefox addon ID and marketplace metadata, create unversioned release artifact

[Copilot]

Prepares the addon for Firefox marketplace submission and enables direct linking to latest release version.

Changes

manifest.json

• Added browser_specific_settings.gecko:
  • id: dom-time-machine@scolasti.co
  • data_collection_permissions: false
  • update_url: Points to latest GitHub release xpi
• Added required marketplace fields: description, author, homepage_url
• Moved icons to top level for marketplace compatibility

release-build.yml

• Creates both versioned (dom-time-machine-v{VERSION}.zip) and unversioned (dom-time-machine.xpi) artifacts
• Unversioned artifact enables stable URL: https://github.com/scolastico-dev/dom-time-machine/releases/latest/download/dom-time-machine.xpi

"browser_specific_settings": {
  "gecko": {
    "id": "dom-time-machine@scolasti.co",
    "data_collection_permissions": false,
    "update_url": "https://github.com/scolastico-dev/dom-time-machine/releases/latest/download/dom-time-machine.xpi"
  }
}

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[github-actions]

🎉 Addon Build Complete

The addon has been successfully built for this PR!

Version: IN-DEV
Build: #21435744703

You can download the built addon from the artifacts section of the workflow run.

Installation Instructions

1. Download the artifact from the workflow run
2. Extract the zip file
3. Load the extension in your browser:
   • Firefox: Navigate to about:debugging#/runtime/this-firefox, click "Load Temporary Add-on", and select the manifest.json
   • Chrome: Navigate to chrome://extensions, enable "Developer mode", click "Load unpacked", and select the extracted folder