增加多平台（Desktop、Android平台支持）

mul/BBIT_AI/composeApp/src/desktopMain/kotlin/com/bbitcn/bbit_ai/Platform.jvm.kt

@@ -0,0 +1,7 @@
+package com.bbitcn.bbit_ai
+
+class JVMPlatform: Platform {
+    override val name: String = "Java ${System.getProperty("java.version")}"
+}
+
+actual fun getPlatform(): Platform = JVMPlatform()

mul/BBIT_AI/composeApp/src/desktopMain/kotlin/com/bbitcn/bbit_ai/main.kt

@@ -0,0 +1,13 @@
+package com.bbitcn.bbit_ai
+
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+
+fun main() = application {
+    Window(
+        onCloseRequest = ::exitApplication,
+        title = "BBIT_AI",
+    ) {
+        App()
+    }
+}