Add Capacitor Android packaging (APK) for Cafe Bazaar / Myket

- Next static export (output: export) wrapped by Capacitor; appId
  com.bargevasat.app, appName «برگ وسط»
- android/ native project + @capacitor/app; hardware back handled by
  CapacitorBack (back a screen, exit at home)
- npm scripts (cap:sync, android:open, android:apk), ANDROID.md
- Gradle Maven-mirror init-script template (dl.google.com/Maven Central are
  blocked in Iran — same reason NuGet is mirrored)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

android/app/capacitor.build.gradle

@@ -0,0 +1,19 @@
+// DO NOT EDIT THIS FILE! IT IS GENERATED EACH TIME "capacitor update" IS RUN
+
+android {
+  compileOptions {
+      sourceCompatibility JavaVersion.VERSION_21
+      targetCompatibility JavaVersion.VERSION_21
+  }
+}
+
+apply from: "../capacitor-cordova-android-plugins/cordova.variables.gradle"
+dependencies {
+    implementation project(':capacitor-app')
+
+}
+
+
+if (hasProperty('postBuildExtras')) {
+  postBuildExtras()
+}