Migrates 38 HTTP polling loops to WebSocket push events across 6 phases: service status, dashboard stats, enrichment workers, tool progress, sync/discovery progress, and scan status. All original HTTP polling is preserved as automatic fallback — if WebSocket is unavailable or disconnects, the app seamlessly reverts to its previous behavior. Includes 162 tests verifying event delivery, data shape, and HTTP parity. Also fixes a copy-paste bug in Beatport sync error cleanup.
