Loading: Prefetch scene metadata and asset count before showing loading screen

### Description
When entering a scene, the loading screen can appear "empty" for several seconds (reported: over 10s) before scene metadata (name, author, thumbnail) and asset progress data show up. During this window the progress bar sits at `0000/0000 resources at 000.00 mb/s - Opt` and `0%`, giving the impression the loading process has stalled or hasn't started.

### Suggested Improvement
Prefetch the scene metadata (name, author/thumbnail) and total asset count before displaying the loading screen (or as early as possible within it), so the screen never shows a blank/zeroed state. This would let the progress bar and scene title populate immediately instead of several seconds in.

### Screenshots
See attached screenshots:
1. Loading screen showing no scene name/thumbnail, `0000/0000 resources`, `0%` progress
2. Same loading screen ~seconds later, now showing "Candy Sheep Meadow" by Hancos with populated progress bar at `11%`

### Context
Reported during real-world usage — noticeable delay (10+ seconds) before any loading feedback appears, which can make the client feel unresponsive or broken during that window.

Requested by Gino Cingolani via Slack