Switch the editor timeline between frames and milliseconds

The challenge
Today the editing timeline shows time only in milliseconds. Many users — especially those coming from a traditional, frame-based video-editing background — are more used to thinking in frames than in milliseconds. A millisecond-only timeline feels unfamiliar to them and makes it harder to navigate and trim precisely.

Our approach
Add a toggle in the editor that switches the timeline's time display between milliseconds and frames (based on the project's frame rate). Let's also explore letting users set their preferred unit as a default for their account or profile in the settings, so the timeline always opens in the format they're most comfortable with.

Expected impact

• Users who are used to frame-based editing can work in the unit they already know
• Easier, more precise navigation and trimming along the timeline
• A more approachable editor for people coming from traditional video-editing tools
• A saved default applies each user's preferred unit automatically