Add tests and cleanup redirects

The changes include:
1. Adding GitHub Actions test job
2. Adding redirect tests
3. Updating redirect configurations
4. Migrating some redirects to SvelteKit routes
5. Test config improvements

tests/redirects.test.ts

@@ -0,0 +1,10 @@
+import { expect, test } from '@playwright/test';
+import redirects from '../src/redirects.json' with { type: 'json' };
+
+redirects.forEach(({ link, redirect }) => {
+    test(`redirected from ${link} to ${redirect} exists`, async ({ page }) => {
+        const response = await page.goto(redirect);
+
+        expect(response?.ok()).toBeTruthy();
+    });
+});