[Feature Request] Timeline "Event Track" (Command Triggers)

[Imagenum]

The Problem: If I have a camera flying through a scene, I often need world events to happen in perfect sync (e.g., a door opening, particles spawning, or lightning striking). Currently, syncing these events to a moving camera requires complex math and tick-delay calculations.

The Solution: Add an "Event Track" to the Camera Sequencer (requested separately).

Function: Allow us to place "Command Keyframes" on the timeline.

Usage: "At 5.0 seconds (Frame 300), execute /setblock ... or /particle ...".

Preview: Ideally, scrubbing the timeline would trigger these events so we can preview the timing in the editor without running the full game simulation.