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/settings.gradle

@@ -0,0 +1,5 @@
+include ':app'
+include ':capacitor-cordova-android-plugins'
+project(':capacitor-cordova-android-plugins').projectDir = new File('./capacitor-cordova-android-plugins/')
+
+apply from: 'capacitor.settings.gradle'