Added

• Add admin page for managing OAuth access tokens.
• Add support for auto-approve followers. (fixes #26)
• Add support for auto-follow back.

Fixed

• Prevent triggering actor refresh when user is anonymous.

Changed

• Replace "lightgallery" dependency with custom image viewer.
• Set OAuth access token expiry to 30 days (previously expired after 24 hours).
• Refactor inbox and outbox processing into dedicated processor services.