core-locale: shared per-app language plumbing (AppLanguage)

Android-library module, drawn from the byte-identical AppLanguage in Agendula
and Calendula: read the shipped languages from res/xml/locales_config.xml,
get/set the applied language via AppCompatDelegate, and render each language's
autonym. The locales_config resource id is now a parameter, so the module is
app-agnostic. appcompat only, no Compose.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core-locale/build.gradle.kts

@@ -0,0 +1,46 @@
+// core-locale — per-app language plumbing shared across the family: read the
+// shipped languages from res/xml/locales_config.xml, get/set the applied
+// language via AppCompatDelegate, and render each language's autonym. App-
+// agnostic — the consuming app passes its own locales_config resource id; no
+// Compose, no DataStore.
+plugins {
+    alias(libs.plugins.android.library)
+}
+
+android {
+    namespace = "de.jeanlucmakiola.floret.locale"
+    compileSdk = 37
+
+    defaultConfig {
+        minSdk = 29
+    }
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    testOptions {
+        unitTests {
+            all { it.useJUnitPlatform() }
+            isReturnDefaultValues = true
+        }
+    }
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+    }
+}
+
+dependencies {
+    // appcompat brings AppCompatDelegate plus its core (LocaleListCompat) and
+    // annotation (XmlRes) transitives.
+    implementation(libs.androidx.appcompat)
+
+    testImplementation(libs.junit.jupiter.api)
+    testRuntimeOnly(libs.junit.jupiter.engine)
+    testRuntimeOnly(libs.junit.platform.launcher)
+    testImplementation(libs.truth)
+}