feat: add easter egg toast message logic with tests

core/src/main/kotlin/plus/rua/project/ui/AboutScreen.kt

@@ -34,6 +34,19 @@ import plus.rua.project.AppInfo
 import plus.rua.project.getAppIconUri
 import plus.rua.project.getAppVersion
 
+/**
+ * 根据当前连续点击次数返回应显示的 Toast 文案。
+ *
+ * @param clickCount 当前连续点击次数（从 1 开始）
+ * @return 需要显示的文案，若无需提示则返回 null
+ */
+internal fun getToastMessage(clickCount: Int): String? = when (clickCount) {
+    4 -> "再点击 3 下进入小狗乐园"
+    5 -> "再点击 2 下进入小狗乐园"
+    6 -> "再点击 1 下进入小狗乐园"
+    else -> null
+}
+
 /**
  * 关于页面，展示应用图标、名称、版本号及开源许可入口。
  *

core/src/test/kotlin/plus/rua/project/ui/AboutEasterEggTest.kt

@@ -0,0 +1,35 @@
+package plus.rua.project.ui
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNull
+
+class AboutEasterEggTest {
+
+    @Test
+    fun `first three clicks show no toast`() {
+        assertNull(getToastMessage(1))
+        assertNull(getToastMessage(2))
+        assertNull(getToastMessage(3))
+    }
+
+    @Test
+    fun `fourth click shows remaining three`() {
+        assertEquals("再点击 3 下进入小狗乐园", getToastMessage(4))
+    }
+
+    @Test
+    fun `fifth click shows remaining two`() {
+        assertEquals("再点击 2 下进入小狗乐园", getToastMessage(5))
+    }
+
+    @Test
+    fun `sixth click shows remaining one`() {
+        assertEquals("再点击 1 下进入小狗乐园", getToastMessage(6))
+    }
+
+    @Test
+    fun `seventh click triggers navigation and shows no toast`() {
+        assertNull(getToastMessage(7))
+    }
+}