fix: correct Thorium API usage

- Import Mapping.* instead of data.mapping.* (mapping/text live in companion object)
- Use Mapping("field", text) for single-field binding instead of mapping[String]
- Pass request explicitly: bindFromRequest()(using request)
- Replace .as(String) with .as(MediaType.JSON) / .as(MediaType.HTML_UTF_8)
- Remove 'implicit' from Action lambda (Scala 3 uses 'using' instead)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main/scala/TaskController.scala

@@ -1,37 +1,39 @@
 import com.greenfossil.thorium.{*, given}
-import com.greenfossil.data.mapping.{*, given}
+import com.greenfossil.data.mapping.Mapping
+import com.greenfossil.data.mapping.Mapping.*
+import com.linecorp.armeria.common.MediaType
 import com.linecorp.armeria.server.annotation.{Get, Post, Param}
 import java.util.UUID
 
 object TaskController:
 
-  private val titleForm = mapping[String]("title" -> text)
+  private val titleField = Mapping("title", text)
 
   @Get("/health")
-  def health = Action: request =>
-    Ok("""{"status":"ok"}""").as("application/json")
+  def health = Action: _ =>
+    Ok("""{"status":"ok"}""").as(MediaType.JSON)
 
   @Get("/")
-  def index = Action: request =>
-    Ok(renderPage()).as("text/html; charset=utf-8")
+  def index = Action: _ =>
+    Ok(renderPage()).as(MediaType.HTML_UTF_8)
 
   @Post("/tasks")
-  def create = Action: implicit request =>
-    titleForm.bindFromRequest().fold(
-      _ => Redirect("/"),
-      title =>
+  def create = Action: request =>
+    val bound = titleField.bindFromRequest()(using request)
+    if bound.hasErrors then Redirect("/")
+    else
+      val title = bound.typedValueOpt.get
       if title.trim.nonEmpty then TaskStore.add(title)
       Redirect("/")
-    )
 
   @Post("/tasks/:id/toggle")
-  def toggle(@Param id: String) = Action: request =>
+  def toggle(@Param id: String) = Action: _ =>
     try TaskStore.toggle(UUID.fromString(id))
     catch case _: IllegalArgumentException => ()
     Redirect("/")
 
   @Post("/tasks/:id/delete")
-  def delete(@Param id: String) = Action: request =>
+  def delete(@Param id: String) = Action: _ =>
     try TaskStore.delete(UUID.fromString(id))
     catch case _: IllegalArgumentException => ()
     Redirect("/")