feat(android): Capacitor wrapper bundling the Fabric web frontend

Greenfield Android client built as a Capacitor shell (mirrors the
Desktop strategy — reuses the React SPA 100%):
- appId ai.hangman.fabric, appName Fabric, androidScheme http +
  usesCleartextTraffic (talks to the http Center/Guild backends; the
  login screen sets the Center base, so a phone points at a LAN/host
  URL instead of localhost).
- scripts/build-web.mjs builds Fabric.Frontend and copies dist -> www;
  npm run sync / apk:debug wire it to Gradle.
- Native android/ project (cap add android) committed; build outputs,
  www/, node_modules, local.properties gitignored.
- Launcher icons = the Fabric mark (adaptive: green mark on black,
  legacy + round) at all densities.

Verified: gradlew assembleDebug -> app-debug.apk (4.2MB) containing
assets/public/index.html + the SPA bundle + Fabric icons.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/gradle.properties

@@ -0,0 +1,22 @@
+# Project-wide Gradle settings.
+
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx1536m
+
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app's APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true