Build all apps from Markdown content; Compose Desktop replaces GTK on Linux and Windows

- content/ + scripts/build-content.py produce content.json for every app
- stable lesson IDs with one-time progress migration (Swift, Kotlin)
- shared answer-check tests (tests/answers.json) for Kotlin and Swift
- android/desktop: Compose app with updater, speech and GTK progress import
- CI packages AppImage and Windows zip with ProGuard, runs the tests

Co-authored-by: Cursor <cursoragent@cursor.com>

android/desktop/build.gradle.kts

@@ -0,0 +1,103 @@
+// Linux and Windows app: the same Compose UI as Android (../shared), packaged
+// with its own Java runtime by jpackage.
+plugins {
+    id("org.jetbrains.kotlin.jvm")
+    id("org.jetbrains.kotlin.plugin.compose")
+    id("org.jetbrains.compose")
+}
+
+val commit: String = System.getenv("COMMIT")?.takeIf { it.isNotBlank() } ?: "dev"
+val repoRoot: File = rootProject.projectDir.parentFile
+val generated = layout.buildDirectory.dir("generated/resources")
+
+kotlin {
+    compilerOptions {
+        jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17)
+    }
+    sourceSets.named("main") {
+        kotlin.srcDir("../shared/src")
+    }
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
+}
+
+sourceSets.named("main") {
+    resources.srcDir(generated)
+}
+
+dependencies {
+    implementation(compose.desktop.currentOs)
+    implementation(compose.material3)
+    implementation("org.jetbrains.compose.material:material-icons-extended:1.7.3")
+    implementation("org.json:json:20250517")
+    testImplementation(kotlin("test"))
+}
+
+val buildContent = tasks.register<Exec>("buildContent") {
+    val out = generated.get().file("content.json").asFile
+    workingDir = repoRoot
+    val python = System.getenv("PYTHON")?.takeIf { it.isNotBlank() }
+        ?: if (System.getProperty("os.name").startsWith("Windows")) "python" else "python3"
+    commandLine(python, "scripts/build-content.py", "--out", out.path)
+    inputs.dir(repoRoot.resolve("content"))
+    inputs.file(repoRoot.resolve("scripts/build-content.py"))
+    outputs.file(out)
+}
+
+val buildInfo = tasks.register("buildInfo") {
+    val out = generated.get().file("build-info.properties").asFile
+    inputs.property("commit", commit)
+    outputs.file(out)
+    doLast {
+        out.parentFile.mkdirs()
+        out.writeText("commit=$commit\n")
+    }
+}
+
+val appIcon = tasks.register<Copy>("appIcon") {
+    from(repoRoot.resolve("data/share/icons/hicolor/256x256/apps/maturita.png"))
+    into(generated)
+    rename { "icon.png" }
+}
+
+tasks.named("processResources") {
+    dependsOn(buildContent, buildInfo, appIcon)
+}
+
+tasks.withType<Test>().configureEach {
+    useJUnitPlatform()
+    systemProperty("graduately.repo", repoRoot.path)
+}
+
+compose.desktop {
+    application {
+        mainClass = "org.maturita.maturita.desktop.MainKt"
+        // jpackage and ProGuard need a JDK with jmods (Temurin 21 has them, 24+ may not).
+        System.getenv("PACKAGE_JDK")?.takeIf { it.isNotBlank() }?.let { javaHome = it }
+        // Shrinking drops the thousands of unused icons and keeps the
+        // packages under GitHub's 100 MB file limit.
+        buildTypes.release.proguard {
+            version.set("7.10.0")
+            obfuscate.set(false)
+            configurationFiles.from(project.file("proguard-rules.pro"))
+        }
+        nativeDistributions {
+            // The launcher must stay graduately(.exe): installers and the
+            // updater of older builds start it by that name.
+            packageName = "graduately"
+            packageVersion = "1.0.0"
+            description = "Graduately"
+            vendor = "Graduately"
+            modules("java.naming", "jdk.crypto.ec", "jdk.unsupported")
+            linux {
+                iconFile.set(repoRoot.resolve("data/share/icons/hicolor/512x512/apps/maturita.png"))
+            }
+            windows {
+                iconFile.set(repoRoot.resolve("assets/app-icon.ico"))
+            }
+        }
+    }
+}