feat: initialize GaCy Android project foundation (Kotlin, Jetpack Compose, Material 3)

app/src/main/java/com/gacy/android/service/LogBuffer.kt

@@ -0,0 +1,38 @@
+package com.gacy.android.service
+
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+
+object LogBuffer {
+
+    private const val MAX_LOG_LINES = 500
+    private val timeFormat = SimpleDateFormat("HH:mm:ss", Locale.getDefault())
+
+    private val _logs = MutableStateFlow<List<String>>(emptyList())
+    val logs: StateFlow<List<String>> = _logs.asStateFlow()
+
+    @Synchronized
+    fun append(message: String) {
+        val timestamp = timeFormat.format(Date())
+        val formatted = "[$timestamp] $message"
+        val current = _logs.value.toMutableList()
+        current.add(formatted)
+        if (current.size > MAX_LOG_LINES) {
+            current.removeAt(0)
+        }
+        _logs.value = current
+    }
+
+    @Synchronized
+    fun clear() {
+        _logs.value = emptyList()
+    }
+
+    fun getAllText(): String {
+        return _logs.value.joinToString("\n")
+    }
+}