Browse redesign: toggle pills, loading bar, entity labels first

- Module toggle pills at top of sidebar (colored per module)
- YouTube-style top loading bar during fetch
- Entity count badge
- Entity items: label prominent, type badge secondary
- Advanced URL loader collapsed by default
- OntologyGraph: force-directed canvas (too dense, needs curation)
- Nav: v3.5 link needs updating to v3.5-alpha6

Author: styk-tv