P0.2: Android test infrastructure (TDD foundation)

- Add androidUnitTest source set: JUnit 4, Robolectric 4.14.1, mockk, androidx.test
- Add androidInstrumentedTest source set: androidx.test.ext, espresso, mockk-android
- Pin Robolectric to SDK 34 (Robolectric 4.14.1 doesn't yet support compileSdk 36)
- Enable includeAndroidResources for Robolectric
- Canary tests green on both source sets

Verifies:
  ./gradlew :composeApp:testDebugUnitTest
  ./gradlew :composeApp:compileDebugAndroidTestSources

Part of Android -> iOS parity plan (rc-android-ios-parity.md).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

composeApp/src/androidUnitTest/kotlin/com/tt/honeyDue/CanaryUnitTest.kt

@@ -0,0 +1,22 @@
+package com.tt.honeyDue
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+
+@RunWith(RobolectricTestRunner::class)
+class CanaryUnitTest {
+
+    @Test
+    fun arithmetic_sanity() {
+        assertEquals(2, 1 + 1)
+    }
+
+    @Test
+    fun robolectric_android_runtime_available() {
+        val appContext = androidx.test.core.app.ApplicationProvider.getApplicationContext<android.content.Context>()
+        assertTrue(appContext.packageName.startsWith("com.tt.honeyDue"))
+    }
+}

composeApp/src/androidUnitTest/resources/robolectric.properties

@@ -0,0 +1 @@
+sdk=34