Adds a dedicated Quality collapsible section: bloom quality dropdown
(Off/Low/Medium/High), bloom threshold/strength, exposure, resolution
scale, star AA toggle. Changing bloom quality at runtime triggers a
pipeline rebuild (despawn bloom entities + respawn via spawn_bloom_pipeline
helper). MSAA honestly labeled as decorative.
Note: the rebuild currently re-spawns the full 3-level pyramid whenever
bloom is enabled (Off vs On). Partial pyramids for Low/Medium are a
future enhancement.