app: installable APK — core-probe (device-tier) + Compose UI

First assembling build of the production app. Android toolchain mirrors
the prober (AGP 9 built-in Kotlin; applying kotlin.android too
double-registers the kotlin extension — the one gotcha).

core-probe (Android lib): Probe→core-measurement Test abstraction;
NetworkInventory (LinkProperties→networks[]), LinkSnapshotProbe,
per-network IcmpProbe (ported from the prober's validated logic).

app (Compose): RunViewModel orchestrates probes into a MeasurementDocument
with a §7.3 summary + first-pass findings; UI renders traffic lights,
networks, tests, findings; JSON export. Rotation-safe (ViewModel).
App-tier only; server-facing (core-engine) + Shizuku are additive
follow-ups. Debug APK 9.5 MB, assembles clean.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

echolot-app/core-probe/build.gradle.kts

@@ -0,0 +1,31 @@
+// SPDX-FileCopyrightText: 2026 Echolot contributors
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+plugins {
+    // AGP 9 has built-in Kotlin — do NOT also apply kotlin.android (double-registers
+    // the `kotlin` extension). Only the serialization compiler plugin is added.
+    alias(libs.plugins.android.library)
+    alias(libs.plugins.kotlin.serialization)
+}
+
+// Device-tier probes (Android platform APIs), emitting core-measurement Test
+// objects. Ported/adapted from the validated echolot-prober. minSdk 26 to
+// match the prober and the feasibility findings.
+android {
+    namespace = "app.echo_lot.probe"
+    compileSdk = 36
+
+    defaultConfig {
+        minSdk = 26
+    }
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+}
+
+dependencies {
+    implementation(project(":core-measurement"))
+    implementation(libs.kotlinx.serialization.json)
+    implementation(libs.kotlinx.coroutines.android)
+}