test(jetbrains): snapshot captured log messages

packages/kilo-jetbrains/backend/src/test/kotlin/ai/kilocode/backend/testing/TestLog.kt

@@ -6,29 +6,31 @@ import ai.kilocode.log.KiloLog
  * Test logger that captures messages for assertions and prints to stdout.
  */
 class TestLog : KiloLog {
-    val messages = mutableListOf<String>()
+    private val items = mutableListOf<String>()
+    val messages: List<String>
+        get() = synchronized(items) { items.toList() }
     override var isDebugEnabled: Boolean = true
 
     override fun debug(block: () -> String) {
         if (!isDebugEnabled) return
         val msg = block()
-        synchronized(messages) { messages.add("DEBUG: $msg") }
+        synchronized(items) { items.add("DEBUG: $msg") }
         println("[test] DEBUG: $msg")
     }
 
     override fun info(msg: String) {
-        synchronized(messages) { messages.add("INFO: $msg") }
+        synchronized(items) { items.add("INFO: $msg") }
         println("[test] INFO: $msg")
     }
 
     override fun warn(msg: String, t: Throwable?) {
-        synchronized(messages) { messages.add("WARN: $msg") }
+        synchronized(items) { items.add("WARN: $msg") }
         println("[test] WARN: $msg")
         t?.printStackTrace()
     }
 
     override fun error(msg: String, t: Throwable?) {
-        synchronized(messages) { messages.add("ERROR: $msg") }
+        synchronized(items) { items.add("ERROR: $msg") }
         System.err.println("[test] ERROR: $msg")
         t?.printStackTrace()
     }