refactor: consolidate formatting utilities and add testing infrastructure

- Replace 8 duplicate formatCurrency functions with shared utility
- Add comprehensive formatter utilities (currency, date, number, etc.)
- Set up Vitest for unit testing with 38 passing tests
- Set up Playwright for E2E testing
- Consolidate database connection to single source (src/utils/db.ts)
- Add auth middleware helpers to reduce code duplication
- Fix display bug: remove spurious minus sign in recent activity amounts
- Add path aliases for cleaner imports ($utils, $models)
- Add project documentation (CODEMAP.md, REFACTORING_PLAN.md)

Test coverage: 38 unit tests passing
Build: successful with no breaking changes

src/routes/mario-kart/+page.server.ts

@@ -0,0 +1,24 @@
+import type { PageServerLoad } from './$types';
+import { error } from '@sveltejs/kit';
+import { dbConnect } from '$utils/db';
+import { MarioKartTournament } from '$models/MarioKartTournament';
+
+export const load: PageServerLoad = async () => {
+	try {
+		await dbConnect();
+
+		const tournaments = await MarioKartTournament.find()
+			.sort({ createdAt: -1 })
+			.lean({ flattenMaps: true });
+
+		// Convert MongoDB documents to plain objects for serialization
+		const serializedTournaments = JSON.parse(JSON.stringify(tournaments));
+
+		return {
+			tournaments: serializedTournaments
+		};
+	} catch (err) {
+		console.error('Error loading tournaments:', err);
+		throw error(500, 'Failed to load tournaments');
+	}
+};