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/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.11.1-all.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists