fix(core): show [swarm-db] source tag in event log

The source tag was being put inside properties instead of at the
top level of SSEEventInfo. formatSSEEvent checks event.source,
not event.properties.source.

Now events from swarm-db polling show [swarm-db] tag instead of [sse].

Author: joelhooks

packages/core/src/world/merged-stream.ts

@@ -264,11 +264,9 @@ export function createMergedWorldStream(config: MergedStreamConfig = {}): Merged
 								: { raw: event.data }
 
 						onEvent({
+							source: event.source, // Top-level source for formatSSEEvent
 							type: event.type,
-							properties: {
-								...properties,
-								source: event.source, // Include source tag for CLI display
-							},
+							properties,
 						})
 					}
 				}),