feat: OTA校验通过后调用PackageInstaller真正安装APK

- SHA256通过→installApk()→PackageInstaller Session API
- 安装完成后通知栏提示重启
- 权限检查: canRequestPackageInstalls()

packages/client-android/android/app/src/main/java/dev/yuzu/gca/MainActivity.kt

@@ -1,5 +1,8 @@
 package dev.yuzu.gca
 
+import android.app.PendingIntent
+import android.content.Intent
+import android.content.pm.PackageInstaller
 import android.graphics.Color
 import android.os.Bundle
 import android.widget.Button
@@ -161,6 +164,14 @@ class MainActivity : AppCompatActivity() {
         val actualSha256 = computeSha256(apkFile)
         if (actualSha256 == manifestSha256) {
             appendLog("  ✅ SHA256 校验通过!")
+            // 5. 安装 APK
+            appendLog("[5/5] 提交安装...")
+            try {
+                installApk(apkFile)
+                appendLog("  ✅ 安装已提交，稍后通知栏点击重启")
+            } catch (e: Exception) {
+                appendLog("  ❌ 安装失败: ${e.message}")
+            }
         } else {
             appendLog("  ❌ SHA256 校验失败!")
             appendLog("  expected: ${manifestSha256.take(32)}")
@@ -192,6 +203,33 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
+    private fun installApk(apkFile: File) {
+        if (!packageManager.canRequestPackageInstalls()) {
+            throw SecurityException("需要允许安装未知应用权限")
+        }
+        val packageInstaller = packageManager.packageInstaller
+        val params = PackageInstaller.SessionParams(PackageInstaller.SessionParams.MODE_FULL_INSTALL)
+        val sessionId = packageInstaller.createSession(params)
+        val session = packageInstaller.openSession(sessionId)
+        try {
+            apkFile.inputStream().use { input ->
+                session.openWrite("package", 0, apkFile.length()).use { output ->
+                    input.copyTo(output)
+                    session.fsync(output)
+                }
+            }
+            val launchIntent = packageManager.getLaunchIntentForPackage(packageName)
+                ?: throw Exception("无法获取启动Intent")
+            val pendingIntent = PendingIntent.getActivity(
+                this, 0, launchIntent,
+                PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+            )
+            session.commit(pendingIntent.intentSender)
+        } finally {
+            session.close()
+        }
+    }
+
     private fun computeSha256(file: File): String {
         val digest = MessageDigest.getInstance("SHA-256")
         file.inputStream().use { input ->