Refactor spinner creation to simplify SpinnerHandle[cats.Id] to SpinnerNoFx

- Also update the example with `SpinnerNoFx`
- Add Scala cross-version build

Author: kevin-lee

build.sbt

@@ -21,7 +21,8 @@ ThisBuild / scmInfo :=
 
 lazy val root = (project in file("."))
   .settings(
-    name := props.ProjectName
+    name := props.ProjectName,
+    crossScalaVersions := props.CrossScalaVersions,
   )
   .settings(noPublish)
   .aggregate(

modules/core/shared/src/main/scala-2/just/spinner/package.scala

@@ -0,0 +1,8 @@
+package just
+
+/** @author Kevin Lee
+  * @since 2026-03-28
+  */
+package object spinner {
+  type SpinnerNoFx = SpinnerHandle[cats.Id]
+}

modules/core/shared/src/main/scala-3/just/spinner/types.scala

@@ -0,0 +1,6 @@
+package just.spinner
+
+/** @author Kevin Lee
+  * @since 2026-03-28
+  */
+type SpinnerNoFx = SpinnerHandle[cats.Id]

modules/core/shared/src/main/scala/just/spinner/Spinner.scala

@@ -33,7 +33,7 @@ object Spinner {
   ): F[SpinnerHandle[F]] =
     SpinnerHandle[F](config, output, timer, mkRef)
 
-  def createDefaultSideEffect(config: SpinnerConfig): SpinnerHandle[cats.Id] = {
+  def createDefaultSideEffect(config: SpinnerConfig): SpinnerNoFx = {
     import effectie.instances.id.fx.idFx
     create[cats.Id](config, TerminalOutput.stderr[cats.Id], SpinnerTimer.create, SpinnerRefMaker.atomicRef[cats.Id])
   }

modules/example-js/src/main/scala/example/Main.scala

@@ -1,8 +1,6 @@
 package example
 
-import cats.Id
-import effectie.instances.id.fx._
-import just.spinner._
+import just.spinner.*
 
 import scala.concurrent.{Future, Promise}
 import scala.concurrent.ExecutionContext.Implicits.global
@@ -18,8 +16,8 @@ object Main {
     p.future
   }
 
-  private def createSpinner(config: SpinnerConfig): SpinnerHandle[Id] =
-    Spinner.create[Id](config, TerminalOutput.stderr[Id], SpinnerTimer.create, SpinnerRefMaker.atomicRef[Id])
+  private def createSpinner(config: SpinnerConfig): SpinnerNoFx =
+    Spinner.createDefaultSideEffect(config)
 
   private def scenario1(): Future[Unit] = {
     println("\n=== Scenario 1: Basic spinner with succeed ===")