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

libs/common-http/src/main/kotlin/ru/ysu/lms/common/ApiError.kt

@@ -0,0 +1,21 @@
+package ru.ysu.lms.common
+
+import java.time.Instant
+
+/**
+ * Uniform error payload, close to RFC 9457 "Problem Details for HTTP APIs".
+ */
+data class ApiError(
+    val type: String = "about:blank",
+    val title: String,
+    val status: Int,
+    val detail: String? = null,
+    val code: String? = null,
+    val violations: List<FieldViolation> = emptyList(),
+    val timestamp: Instant = Instant.now(),
+)
+
+data class FieldViolation(
+    val field: String,
+    val message: String,
+)

libs/common-http/src/main/kotlin/ru/ysu/lms/common/Ids.kt

@@ -0,0 +1,21 @@
+package ru.ysu.lms.common
+
+import java.security.SecureRandom
+import java.util.UUID
+
+/**
+ * Time-ordered UUIDv7 identifiers (the same layout PostgreSQL 18 provides with
+ * `uuidv7()`), so application-generated and database-generated ids match.
+ */
+object Ids {
+    private val random = SecureRandom()
+
+    fun v7(): UUID {
+        val timestamp = System.currentTimeMillis() and 0x0000_FFFF_FFFF_FFFFL
+        val randA = (random.nextInt() and 0x0FFF).toLong()
+        val randB = random.nextLong() and 0x3FFF_FFFF_FFFF_FFFFL
+        val msb = (timestamp shl 16) or 0x7000L or randA
+        val lsb = Long.MIN_VALUE or randB
+        return UUID(msb, lsb)
+    }
+}

libs/common-http/src/main/kotlin/ru/ysu/lms/common/LmsCommonAutoConfiguration.kt

@@ -0,0 +1,13 @@
+package ru.ysu.lms.common
+
+import org.springframework.boot.autoconfigure.AutoConfiguration
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
+import org.springframework.context.annotation.Bean
+
+@AutoConfiguration
+class LmsCommonAutoConfiguration {
+
+    @Bean
+    @ConditionalOnMissingBean
+    fun lmsExceptionHandler(): LmsExceptionHandler = LmsExceptionHandler()
+}

libs/common-http/src/main/kotlin/ru/ysu/lms/common/LmsException.kt

@@ -0,0 +1,29 @@
+package ru.ysu.lms.common
+
+import org.springframework.http.HttpStatus
+
+/**
+ * Base class for expected, domain-level failures. Mapped to [ApiError] by
+ * [LmsExceptionHandler].
+ */
+open class LmsException(
+    val status: HttpStatus,
+    override val message: String,
+    val code: String? = null,
+    val violations: List<FieldViolation> = emptyList(),
+) : RuntimeException(message)
+
+class BadRequestException(message: String, code: String? = null) :
+    LmsException(HttpStatus.BAD_REQUEST, message, code)
+
+class NotFoundException(message: String, code: String? = null) :
+    LmsException(HttpStatus.NOT_FOUND, message, code)
+
+class ConflictException(message: String, code: String? = null) :
+    LmsException(HttpStatus.CONFLICT, message, code)
+
+class ForbiddenException(message: String, code: String? = null) :
+    LmsException(HttpStatus.FORBIDDEN, message, code)
+
+class UnauthorizedException(message: String, code: String? = null) :
+    LmsException(HttpStatus.UNAUTHORIZED, message, code)

libs/common-http/src/main/kotlin/ru/ysu/lms/common/LmsExceptionHandler.kt

@@ -0,0 +1,37 @@
+package ru.ysu.lms.common
+
+import org.springframework.http.ResponseEntity
+import org.springframework.web.bind.MethodArgumentNotValidException
+import org.springframework.web.bind.annotation.ExceptionHandler
+import org.springframework.web.bind.annotation.RestControllerAdvice
+
+@RestControllerAdvice
+class LmsExceptionHandler {
+
+    @ExceptionHandler(LmsException::class)
+    fun handleDomain(ex: LmsException): ResponseEntity<ApiError> =
+        ResponseEntity.status(ex.status).body(
+            ApiError(
+                title = ex.status.reasonPhrase,
+                status = ex.status.value(),
+                detail = ex.message,
+                code = ex.code,
+                violations = ex.violations,
+            ),
+        )
+
+    @ExceptionHandler(MethodArgumentNotValidException::class)
+    fun handleValidation(ex: MethodArgumentNotValidException): ResponseEntity<ApiError> {
+        val violations = ex.bindingResult.fieldErrors.map {
+            FieldViolation(field = it.field, message = it.defaultMessage ?: "invalid value")
+        }
+        return ResponseEntity.badRequest().body(
+            ApiError(
+                title = "Validation failed",
+                status = 400,
+                detail = "Request validation failed",
+                violations = violations,
+            ),
+        )
+    }
+}

libs/common-http/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -0,0 +1 @@
+ru.ysu.lms.common.LmsCommonAutoConfiguration