Add Http4s TodoMVC Example (#4446)

Closes #4433

Author: armanbilge

docs/modules/ROOT/pages/scalalib/web-examples.adoc

@@ -39,4 +39,8 @@ include::partial$example/scalalib/web/7-cross-platform-version-publishing.adoc[]
 
 == Scala.js WebAssembly Example
 
-include::partial$example/scalalib/web/8-wasm.adoc[]
+include::partial$example/scalalib/web/8-wasm.adoc[]
+
+== TodoMVC http4s Web App
+
+include::partial$example/scalalib/web/9-todo-http4s.adoc[]

example/scalalib/web/9-todo-http4s/build.mill

@@ -0,0 +1,41 @@
+package build
+import mill._, scalalib._
+
+object `package` extends RootModule with ScalaModule {
+  def scalaVersion = "2.13.8"
+  def ivyDeps = Agg(
+    ivy"org.http4s::http4s-ember-server::0.23.30",
+    ivy"org.http4s::http4s-dsl::0.23.30",
+    ivy"org.http4s::http4s-scalatags::0.25.2",
+    ivy"io.circe::circe-generic::0.14.10"
+  )
+
+  object test extends ScalaTests {
+    def testFramework = "utest.runner.Framework"
+
+    def ivyDeps = Agg(
+      ivy"com.lihaoyi::utest::0.8.5",
+      ivy"org.typelevel::cats-effect-testing-utest::1.6.0",
+      ivy"org.http4s::http4s-client::0.23.30"
+    )
+  }
+}
+
+// This example demonstrates how to set up a simple Scala webserver
+// implementing the popular Todo-MVC demo application. It includes a test suite
+// that spins up the web server locally and makes HTTP requests against it.
+
+/** Usage
+
+> ./mill test
++ webapp.WebAppTests.simpleRequest...
+
+> ./mill runBackground
+
+> curl http://localhost:8084
+...What needs to be done...
+...
+
+> ./mill clean runBackground
+
+*/