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/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile