Enhance calendar settings dialog and optimize date selection logic

src/app/app.html

@@ -1,6 +1,6 @@
 <app-dark-light-mode-button class="modeButton"></app-dark-light-mode-button>
 <main class="main">
-	<h1>{{ title() }}</h1>
+	<h1 style="display: flex; gap: 1rem"><mat-icon>beach_access</mat-icon> {{ title() }}</h1>
 	<div class="content">
 		<app-user-input></app-user-input>
 		<mat-divider [vertical]="true" />