Continues the Mastodon-compatible API work.

Added

• Cursor-based pagination on actor timeline and everything pages.
• Mastodon-compatible API: /api/v1/statuses endpoint for status posting.
• Mastodon-compatible API: /api/v1/timelines/public endpoint.

Fixed

• Autosave focus handling. Fixes problems introduced in v3.3.3.
• Prevent blur from creating a draft post when publishing a post.

Changed

• Integrate X-Ray Mode colors into the theming system.
• Improve CI: add npm audit, test, and caching.
• Use npm ci in Dockerfile for reproducible builds.
• Remove very old compiler bug work-around.