M15.2: merge main (disk cache, 3D Camera Tracker); camera analysis in workers; no disk cache on wasm32

The 3D Camera Tracker analysis joins the offloaded jobs. The disk cache stays off in the
browser (std::env::temp_dir panics on wasm32 once a config store exists).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/gpu/src/tests.rs

@@ -100,6 +100,7 @@ impl Scene {
             missing: false,
             sequence: vec![],
             color_profile: None,
+            layer: None,
         };
         let fid = self.p.add_item("Pattern", Label::Lavender, None, ItemKind::Footage(f));
         build::layer(&mut self.p, &self.comp, "Pattern", LayerSource::Footage { item: fid }, (w, h), None)