Add booking SSE stream and emit on updates

src/main/kotlin/com/android/trisolarisserver/component/BookingEvents.kt

@@ -0,0 +1,35 @@
+package com.android.trisolarisserver.component
+
+import com.android.trisolarisserver.controller.BookingSnapshotBuilder
+import com.android.trisolarisserver.controller.dto.BookingDetailResponse
+import org.springframework.scheduling.annotation.Scheduled
+import org.springframework.stereotype.Component
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter
+import java.util.UUID
+
+@Component
+class BookingEvents(
+    private val bookingSnapshotBuilder: BookingSnapshotBuilder
+) {
+    private val hub = SseHub<BookingKey>("booking") { key ->
+        bookingSnapshotBuilder.build(key.propertyId, key.bookingId)
+    }
+
+    fun subscribe(propertyId: UUID, bookingId: UUID): SseEmitter {
+        return hub.subscribe(BookingKey(propertyId, bookingId))
+    }
+
+    fun emit(propertyId: UUID, bookingId: UUID) {
+        hub.emit(BookingKey(propertyId, bookingId))
+    }
+
+    @Scheduled(fixedDelayString = "25000")
+    fun heartbeat() {
+        hub.heartbeat()
+    }
+}
+
+private data class BookingKey(
+    val propertyId: UUID,
+    val bookingId: UUID
+)