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/shared/build.gradle.kts

@@ -0,0 +1,34 @@
+plugins {
+    kotlin("multiplatform")
+    id("com.android.library")
+    id("org.jetbrains.compose")
+    id("org.jetbrains.kotlin.plugin.compose")
+}
+
+val composeVersion = "1.7.3"
+
+kotlin {
+    androidTarget()
+    jvm("desktop")
+
+    sourceSets {
+        commonMain.dependencies {
+            implementation("org.jetbrains.compose.runtime:runtime:$composeVersion")
+            implementation("org.jetbrains.compose.foundation:foundation:$composeVersion")
+            implementation("org.jetbrains.compose.material3:material3:$composeVersion")
+            implementation("org.jetbrains.compose.ui:ui:$composeVersion")
+        }
+    }
+}
+
+android {
+    namespace = "iris.shared"
+    compileSdk = 34
+    defaultConfig {
+        minSdk = 29
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+}