Prepare Firefox Add-On deploy

[MartinGroscheTT]

Description

As the add-on maintainer we want to have a fully automated update for the Firefox Add-On.

Acceptance Criteria

• The build process for the Firefox Add-On is automated via GitHub Actions (or equivalent CI pipeline)
• The version number and changelog are updated automatically or through defined workflow steps
• The packaged .xpi file is generated automatically as part of the release workflow
• The Add-On is submitted to Mozilla Add-On (AMO) platform using API and credentials securely stored (e.g. GitHub Secrets)
• Submission includes release notes and required metadata
• The workflow is triggered on tag or release creation
• The process is documented for transparency and future maintenance
• The update process is tested and results are verified (e.g. via status checks or manual review of a test submission)