Enhance CountryController with advanced filtering, sorting, and pagination. Refactor Gradle scripts with version catalogs, improve error code handling, and centralize query models in core-domain.

core/core-domain/src/commonMain/kotlin/at/mocode/core/domain/model/ErrorCodes.kt

@@ -13,4 +13,15 @@ object ErrorCodes {
   val DATABASE_ERROR = ErrorCode("DATABASE_ERROR")
   val TRANSACTION_ERROR = ErrorCode("TRANSACTION_ERROR")
   val VALIDATION_ERROR = ErrorCode("VALIDATION_ERROR")
+  // Allgemeine API-/HTTP-nahe Fehlercodes zur Harmonisierung
+  val INVALID_ID = ErrorCode("INVALID_ID")
+  val NOT_FOUND = ErrorCode("NOT_FOUND")
+  val CREATION_FAILED = ErrorCode("CREATION_FAILED")
+  val UPDATE_FAILED = ErrorCode("UPDATE_FAILED")
+  val DELETE_FAILED = ErrorCode("DELETE_FAILED")
+  val CONFLICT = ErrorCode("CONFLICT")
+  val MISSING_PARAMETER = ErrorCode("MISSING_PARAMETER")
+  val INVALID_PARAMETER = ErrorCode("INVALID_PARAMETER")
+  val UNAUTHORIZED = ErrorCode("UNAUTHORIZED")
+  val FORBIDDEN = ErrorCode("FORBIDDEN")
 }

core/core-domain/src/commonMain/kotlin/at/mocode/core/domain/model/QueryModels.kt

@@ -0,0 +1,36 @@
+package at.mocode.core.domain.model
+
+import kotlinx.serialization.Serializable
+
+/**
+ * Gemeinsame Query-Modelle für Filter, Sortierung und Pagination.
+ */
+
+@Serializable
+enum class SortDirection { ASC, DESC }
+
+@Serializable
+data class SortParam(
+  val field: String,
+  val direction: SortDirection = SortDirection.ASC
+)
+
+@Serializable
+data class PageRequest(
+  val page: PageNumber = PageNumber(0),
+  /**
+   * Wenn size == -1 oder unpaged == true, wird die Paginierung aufgehoben und alle Treffer geliefert.
+   */
+  val size: Int = 20,
+  val sort: List<SortParam> = emptyList(),
+  val unpaged: Boolean = false
+)
+
+@Serializable
+data class FilterParams(
+  val search: String? = null,
+  /**
+   * active: true = nur aktive (Default), false = nur inaktive, all = alle
+   */
+  val active: String? = null
+)