fix(android): add ProGuard rules to suppress HMS missing class errors

R8 fails on missing optional HMS dependencies (HiAnalytics, libcore,
BouncyCastle). Add dontwarn rules and wire proguard-rules.pro to release
build type.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

it0_app/android/app/build.gradle.kts

@@ -79,6 +79,11 @@ android {
             // TODO: Add your own signing config for the release build.
             // Signing with the debug keys for now, so `flutter run --release` works.
             signingConfig = signingConfigs.getByName("debug")
+            isMinifyEnabled = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
         }
     }
 

it0_app/android/app/proguard-rules.pro

@@ -0,0 +1,17 @@
+# Flutter
+-keep class io.flutter.app.** { *; }
+-keep class io.flutter.plugin.** { *; }
+-keep class io.flutter.util.** { *; }
+-keep class io.flutter.view.** { *; }
+-keep class io.flutter.** { *; }
+-keep class io.flutter.plugins.** { *; }
+
+# Huawei HMS — optional internal classes not bundled in the app
+-dontwarn com.huawei.android.os.**
+-dontwarn com.huawei.hianalytics.**
+-dontwarn com.huawei.hms.availableupdate.**
+-dontwarn com.huawei.libcore.io.**
+-dontwarn com.huawei.secure.android.**
+
+# BouncyCastle — referenced by HMS security but not shipped
+-dontwarn org.bouncycastle.**