feat(stats): add platform statistics and landing blocks

Add PlatformStats component to stats page. Extract YearBars from
FinishedStats for reuse on landing. Add three blocks to landing: games
per platform, top genres, finished per year. Update translations.

src/pages/LandingPage.test.jsx

@@ -0,0 +1,45 @@
+// @vitest-environment jsdom
+import {afterEach, describe, expect, it, vi} from 'vitest';
+import {cleanup, render, screen} from '@testing-library/react';
+import {MemoryRouter} from 'react-router-dom';
+import LandingPage from './LandingPage.jsx';
+import {fetchRoutes, json} from '../test/fetchRoutes.js';
+
+vi.mock('react-i18next', () => import('../test/i18n-mock.js'));
+vi.mock('../hooks/useSession.js', () => ({default: () => ({active: false})}));
+
+// Auth and Core answer the same path; one object serves both shapes.
+const answer = (core) => fetchRoutes({'GET /api/stats/public': json(200, {topPlayedGames: [], topOwnedGames: [], ...core})});
+
+const renderPage = () => render(<MemoryRouter><LandingPage/></MemoryRouter>);
+
+describe('LandingPage', () => {
+    afterEach(cleanup);
+
+    it('shows games per platform, top genres and finished per year', async () => {
+        answer({
+            gamesPerPlatform: [{name: 'PS5', games: 3, minutes: 600}],
+            topGenres: [{name: 'Shooter', games: 2, minutes: 1200}],
+            finishedPerYear: [{year: 2025, games: 4}],
+        });
+        renderPage();
+
+        expect(await screen.findByText('LANDING.PLATFORMS')).toBeTruthy();
+        expect(screen.getByText('PS5')).toBeTruthy();
+        expect(screen.getByText('LANDING.TOP_GENRES')).toBeTruthy();
+        expect(screen.getByText('STATS.GENRE.SHOOTER')).toBeTruthy();
+        expect(screen.getByText('LANDING.FINISHED_PER_YEAR')).toBeTruthy();
+        expect(screen.getByText('2025')).toBeTruthy();
+    });
+
+    it('hides the three blocks while their lists are empty', async () => {
+        answer({gamesPerPlatform: [], topGenres: [], finishedPerYear: []});
+        renderPage();
+
+        await screen.findByText('LANDING.STATS_TITLE');
+        await vi.waitFor(() => expect(fetch).toHaveBeenCalledTimes(2));
+        for (const title of ['PLATFORMS', 'TOP_GENRES', 'FINISHED_PER_YEAR']) {
+            expect(screen.queryByText(`LANDING.${title}`)).toBeNull();
+        }
+    });
+});