Update RTLM4 to make reset-to-zero-value clear clearTimeserial per spec 26bda6ffabfe648c9784215ee79e668201c441b8

Author: lawrence-forooghian

Sources/AblyLiveObjects/Internal/InternalDefaultLiveMap.swift

@@ -957,6 +957,7 @@ internal final class InternalDefaultLiveMap: Sendable {
         mutating func resetDataToZeroValued() {
             // RTLM4
             data = [:]
+            clearTimeserial = nil
         }
 
         /// Releases entries that were tombstoned more than `gracePeriod` ago, per RTLM19.

Tests/AblyLiveObjectsTests/InternalDefaultRealtimeObjectsTests.swift

@@ -439,6 +439,11 @@ struct InternalDefaultRealtimeObjectsTests {
             let originalPool = realtimeObjects.testsOnly_objectsPool
             #expect(Set(originalPool.root.testsOnly_data.keys) == ["existingMap", "existingCounter"])
 
+            // Give root a non-nil clearTimeserial so we can verify it gets nilled out per RTLM4
+            // (using a serial before the entry timeserials so entries survive)
+            _ = originalPool.root.testsOnly_applyMapClearOperation(serial: "aaa")
+            #expect(originalPool.root.testsOnly_clearTimeserial == "aaa")
+
             let rootSubscriber = Subscriber<DefaultLiveMapUpdate, SubscribeResponse>(callbackQueue: .main)
             let coreSDK = MockCoreSDK(channelState: .attached, internalQueue: internalQueue)
             try originalPool.root.subscribe(listener: rootSubscriber.createListener(), coreSDK: coreSDK)
@@ -489,6 +494,7 @@ struct InternalDefaultRealtimeObjectsTests {
             let newRoot = newPool.root
             #expect(newRoot as AnyObject === originalPool.root as AnyObject) // Should be same instance
             #expect(newRoot.testsOnly_data.isEmpty) // Should be zero-valued (empty)
+            #expect(newRoot.testsOnly_clearTimeserial == nil) // RTLM4: zero-value LiveMap has clearTimeserial set to null
 
             // RTO4b3, RTO4b4, RTO4b5: SyncObjectsPool must be cleared, sync sequence cleared, BufferedObjectOperations cleared, appliedOnAckSerials cleared
             #expect(!realtimeObjects.testsOnly_hasSyncSequence)