refactor(message-log-api): move TokenStats to a separate file for improved modularity

message-log-api/src/commonMain/kotlin/pw/binom/agentik/messageLog/MessageStore.kt

@@ -3,14 +3,6 @@ package pw.binom.agentik.messageLog
 import kotlinx.coroutines.flow.Flow
 import kotlin.time.Instant
 
-data class TokenStats(
-    val turns: Int,
-    val inputTokens: Long,
-    val outputTokens: Long,
-) {
-    val totalTokens: Long get() = inputTokens + outputTokens
-}
-
 /**
  * Append-only audit log сообщений.
  *

message-log-api/src/commonMain/kotlin/pw/binom/agentik/messageLog/TokenStats.kt

@@ -0,0 +1,9 @@
+package pw.binom.agentik.messageLog
+
+data class TokenStats(
+    val turns: Int,
+    val inputTokens: Long,
+    val outputTokens: Long,
+) {
+    val totalTokens: Long get() = inputTokens + outputTokens
+}