refactor(preview): replace @Preview with @ComponentPreview and update dependencies

- Replaced all occurrences of `@Preview` with the standardized `@ComponentPreview` annotation for a consistent preview experience across modules.
- Added `compose.uiTooling` dependency to `core/design-system` for enhanced preview functionality.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

frontend/core/design-system/build.gradle.kts

@@ -26,5 +26,8 @@ kotlin {
       implementation(compose.components.resources)
       implementation(libs.bundles.kmp.common)
     }
+    jvmMain.dependencies {
+      implementation(compose.uiTooling)
+    }
   }
 }

frontend/core/design-system/src/jvmMain/kotlin/at/mocode/wui/preview/Multipreview.kt

@@ -0,0 +1,23 @@
+package at.mocode.wui.preview
+
+import androidx.compose.ui.tooling.preview.Preview
+
+/**
+ * A standardized preview annotation for UI components.
+ *
+ * This annotation provides a consistent size and background for component previews.
+ * It helps in maintaining a uniform look for previews across the project.
+ *
+ * Groups can be used to organize previews in the IDE.
+ *
+ * Usage:
+ * ```
+ * @ComponentPreview
+ * @Composable
+ * fun MyButtonPreview() {
+ *   MyButton()
+ * }
+ * ```
+ */
+@Preview(showBackground = true, widthDp = 800, heightDp = 400)
+annotation class ComponentPreview