Refactor terminology in dialogs and tables for consistency; update styles for number inputs and footer links

src/Duempelkas.App/Components/Layout/MainLayout.razor

@@ -11,12 +11,34 @@
         @Body
     </main>
 
-    <footer class="app-footer">
-        Dümpelkas &copy; @DateTime.Now.Year &middot; Version @AppVersion
+    <footer class="app-footer d-flex align-items-center justify-content-center gap-2">
+        <span>Dümpelkas &copy; @DateTime.Now.Year &middot; Version @AppVersion</span> &middot;<a class="app-footer-about" @onclick="OpenAboutDialog">Über</a>
     </footer>
 </div>
 
+@if (showAboutDialog)
+{
+    <div class="dialog-backdrop" @onclick="CloseAboutDialog">
+        <div class="dialog-content" @onclick:stopPropagation="true">
+            <h5>Über Dümpelkas &middot; Version @AppVersion</h5>
+            <p class="mb-2">Entwickler: Andre Beging</p>
+            <p class="mb-3">E-Mail: <a href="mailto:mail@beging.de" style="color: white;">mail@beging.de</a></p>
+            <div class="d-flex justify-content-end">
+                <button type="button" class="btn btn-outline-secondary" @onclick="CloseAboutDialog">
+                    <i class="bi bi-x-lg"></i> Schließen
+                </button>
+            </div>
+        </div>
+    </div>
+}
+
 @code {
+    private bool showAboutDialog;
+
+    private void OpenAboutDialog() => showAboutDialog = true;
+
+    private void CloseAboutDialog() => showAboutDialog = false;
+
     private static string AppVersion
     {
         get