M0: toolchain, monorepo scaffold, gateway plugin skeleton, CMP app

- gateway-plugin/: android platform plugin (plugin.yaml + adapter.py
  register(ctx) + no-op AndroidAdapter) + stub modules for M1-M5
- app/: Compose Multiplatform project (shared KMP + androidApp +
  desktopApp) with Gradle wrapper; builds :androidApp:assembleDebug
  and :desktopApp:compileKotlin
- scripts/guard_hermes_agent.sh + pre-commit hook: fail if hermes-agent/
  is staged (read-only reference, never committed)
- .gitignore excludes hermes-agent/; docs/ reference library

app/gradle.properties

@@ -0,0 +1,11 @@
+org.gradle.jvmargs=-Xmx4g -Dfile.encoding=UTF-8
+org.gradle.caching=true
+org.gradle.configuration-cache=true
+
+android.useAndroidX=true
+android.nonTransitiveRClass=true
+
+kotlin.code.style=official
+
+# Compose Multiplatform
+org.jetbrains.compose.experimental.jscanvas.enabled=false