refactor: update submit handlers to return boolean for success indication in label and post dialogs

frontend/src/lib/label/framework/ui/CreateLabelDialog.svelte

@@ -30,7 +30,7 @@
 		onSubmit: createLabel,
 	}: {
 		disabled: boolean;
-		onSubmit: (params: FormParams) => Promise<void>;
+		onSubmit: (params: FormParams) => Promise<boolean>;
 	} = $props();
 
 	let open = $state(false);
@@ -62,7 +62,11 @@
 			return;
 		}
 
-		await createLabel(formData);
+		const isSuccess = await createLabel(formData);
+        if (!isSuccess) {
+            return;
+        }
+
 		formData = {
 			name: '',
 			color: '#dddddd',

frontend/src/lib/label/framework/ui/LabelManagementPage.svelte

@@ -23,7 +23,7 @@
 	const labelsListedState = $derived($labelsListedStore);
 	const { trigger: loadLabels } = labelsListedStore;
 
-	async function onCreateLabelDialogSubmit(params: CreateLabelDialogFormParams) {
+	async function onCreateLabelDialogSubmit(params: CreateLabelDialogFormParams): Promise<boolean> {
 		const colorViewModel = ColorViewModel.fromHex(params.color);
 		const color = colorViewModel.toEntity();
 
@@ -39,7 +39,10 @@
 			toast.error('Failed to create label', {
 				description: state.error.message,
 			});
+			return false;
 		}
+
+		return true;
 	}
 
 	onMount(() => loadLabels());

frontend/src/lib/post/framework/ui/CreatePostDialog.svelte

@@ -30,7 +30,7 @@
 		onSubmit: createPost,
 	}: {
 		disabled: boolean;
-		onSubmit: (params: FormParams) => Promise<void>;
+		onSubmit: (params: FormParams) => Promise<boolean>;
 	} = $props();
 
 	let open = $state(false);
@@ -50,7 +50,11 @@
 			return;
 		}
 
-		await createPost(formData);
+		const isSuccess = await createPost(formData);
+		if (!isSuccess) {
+			return;
+		}
+
 		formData = { semanticId: '', title: '' };
 		open = false;
 	}

frontend/src/lib/post/framework/ui/PostManagementPage.svelte

@@ -22,7 +22,7 @@
 	const postsListedState = $derived($postsListedStore);
 	const { trigger: loadPosts } = postsListedStore;
 
-	async function onCreatePostDialogSubmit(params: CreatePostDialogFormParams) {
+	async function onCreatePostDialogSubmit(params: CreatePostDialogFormParams): Promise<boolean> {
 		const state = await createPost(params);
 
 		if (state.isSuccess()) {
@@ -32,7 +32,10 @@
 			toast.error('Failed to create post', {
 				description: state.error.message,
 			});
+			return false;
 		}
+
+		return true;
 	}
 
 	onMount(() => loadPosts({ showUnpublished: true }));