Silence success toasts on item-tag complete/idle in ShopDetailView

Ports nativeapptemplate/NativeAppTemplate-iOS#52.
The swipe action already reflects the state change via ShopDetailCardView's
re-render after reload(); the extra success toast was redundant noise.
Errors still post to the message bus so users still see feedback when
something actually fails.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dadachi

NativeAppTemplate/Constants.swift

@@ -204,9 +204,7 @@ extension String {
     static let itemTagUpdated = "Tag updated successfully."
     static let itemTagDeleted = "Tag deleted successfully."
     static let itemTagDeletedError = "There was a problem deleting the tag."
-    static let itemTagCompleted = "Tag completed successfully."
     static let itemTagCompletedError = "There was a problem completing the tag."
-    static let itemTagIdled = "Tag idled successfully."
     static let itemTagIdledError = "There was a problem idling the tag."
 
     static let shopkeeperCreated = "Account created successfully."

NativeAppTemplate/UI/Shop Detail/ShopDetailViewModel.swift

@@ -76,7 +76,6 @@ final class ShopDetailViewModel {
 
             do {
                 _ = try await itemTagRepository.complete(id: itemTagId)
-                messageBus.post(message: Message(level: .success, message: .itemTagCompleted))
             } catch {
                 messageBus.post(
                     message: Message(
@@ -98,7 +97,6 @@ final class ShopDetailViewModel {
 
             do {
                 _ = try await itemTagRepository.idle(id: itemTagId)
-                messageBus.post(message: Message(level: .success, message: .itemTagIdled))
             } catch {
                 messageBus.post(
                     message: Message(

NativeAppTemplateTests/UI/Shop Detail/ShopDetailViewModelTest.swift

@@ -143,9 +143,7 @@ struct ShopDetailViewModelTest { // swiftlint:disable:this type_body_length
         }
         await completeTagTask.value
 
-        let message = String.itemTagCompleted
-
-        #expect(viewModel.messageBus.currentMessage?.message == message)
+        #expect(viewModel.messageBus.currentMessage == nil)
     }
 
     @Test
@@ -211,9 +209,7 @@ struct ShopDetailViewModelTest { // swiftlint:disable:this type_body_length
         }
         await idleTagTask.value
 
-        let message = String.itemTagIdled
-
-        #expect(viewModel.messageBus.currentMessage?.message == message)
+        #expect(viewModel.messageBus.currentMessage == nil)
     }
 
     @Test