feat: add update page, refactor update checking process

tests/Feature/Settings/UpdateSettingsTest.php

@@ -0,0 +1,29 @@
+<?php
+
+use App\Settings\UpdateSettings;
+
+test('it has default value for prereleases', function (): void {
+    $settings = app(UpdateSettings::class);
+
+    expect($settings->prereleases)->toBeFalse();
+});
+
+test('it can update prereleases', function (): void {
+    $settings = app(UpdateSettings::class);
+    $settings->prereleases = true;
+    $settings->save();
+
+    $settings->refresh();
+
+    expect($settings->prereleases)->toBeTrue();
+});
+
+test('it persists prereleases across instances', function (): void {
+    $settings1 = app(UpdateSettings::class);
+    $settings1->prereleases = true;
+    $settings1->save();
+
+    $settings2 = app(UpdateSettings::class);
+
+    expect($settings2->prereleases)->toBeTrue();
+});