The timeline ruler's labels pile on top of each other on a long track #710

What happens

Open a long track and the time labels above the lanes run into each other. Reported with a screenshot: a 59 minute compilation imported from YouTube ("邓丽君经典金曲 - Teresa Teng's classic songs") shows 0:00, 1:00, 2:00 and so on up to 58:00, crammed into the mixer's ruler and unreadable.

Why

tickStep() in static/js/transport.js never spaces labels more than 60 seconds apart: 15 s under 90 s, 30 s under five minutes, 60 s for everything longer. At 1x zoom the step does not consider how much room there is, so an hour gets 59 labels in about 1500 px, roughly 25 px each, which is narrower than a "58:00" label.

Who it affects

Anyone working with long material: live sets, DJ mixes, compilations, full albums uploaded as one video, rehearsal recordings.

Constraints for a fix

• The ruler over the lanes and the footer waveform's ruler must produce the same ticks at 1x zoom. They share a left edge and width ([Bug]: Footer waveform is not aligned with the lane waveforms above it #371), and different ticks would put them out of step again. The footer calls tickStep() without a width today.
• Zoom subdivides the ticks, and that should keep working.
• Songs up to about 12 minutes should keep the spacing they have now.

Being worked on in the feat/song-identification branch.