Initial commit: LMS microservices scaffold

- Gradle multi-module: libs/{common-http,security-jwt,markdown,test-support},
  services/{identity,academic,progress,gateway}, web (Thymeleaf+htmx)
- identity-service: JWT auth (RSA), accounts, students, groups, enrollment,
  import from XLSX/CSV, credentials export, password reset
- academic-service: lab import from JSON/zip (markdown + YAML + variants),
  levels, API
- progress-service: schema for student levels and variant assignments
- gateway: Spring Cloud Gateway, JWT validation, route propagation
- web: Server-side UI with flex/footer layout, light/dark theme toggle,
  admin dashboard, groups CRUD, student portal placeholder
- docker-compose: PostgreSQL 18
- Tests: identity smoke test with Testcontainers

buildSrc/build.gradle.kts

@@ -0,0 +1,16 @@
+plugins {
+    // The Kotlin DSL plugin provides a convenient way to develop convention plugins.
+    `kotlin-dsl`
+}
+
+kotlin {
+    jvmToolchain(21)
+}
+
+dependencies {
+    // Plugins applied by the convention plugins in `src/main/kotlin`.
+    implementation(libs.kotlinGradlePlugin)
+    implementation(libs.kotlinAllopenPlugin)
+    implementation(libs.kotlinNoargPlugin)
+    implementation(libs.springBootGradlePlugin)
+}