feat(effects): polish 8 effects and add 7 new engines with parallax

Synthwave, fireflies, snow, sakura, nebula: CSS/SVG. Matrix and
constellation: canvas. Existing engines gain depth, color, glow, and
parallax (mouse and device tilt, opt-in on iOS)

src/pages/PointsPage.test.jsx

@@ -19,6 +19,8 @@ const wallet = (extra = {}) => ({
         {code: 'FX_GOLD_SHINE', slot: 'COMPLETED_EFFECT', price: 300},
         {code: 'BG_GRID', slot: 'PAGE_BACKGROUND', price: 450},
         {code: 'BN_GRID', slot: 'BANNER_BACKGROUND', price: 300},
+        {code: 'BG_SNOW', slot: 'PAGE_BACKGROUND', price: 400},
+        {code: 'BN_MATRIX', slot: 'BANNER_BACKGROUND', price: 300},
         {code: 'BADGE_FINISH_10', slot: 'BADGE', price: 0, track: 'GAMES_FINISHED', target: 10},
         {code: 'BADGE_STREAK_4', slot: 'BADGE', price: 0, track: 'FINISH_WEEKS', target: 4},
         {code: 'SKIN_PASTEL', slot: 'SKIN', price: 600},
@@ -47,7 +49,11 @@ const renderPage = async (routes = {}) => {
     await screen.findByText('POINTS.SHOP');
 };
 
-beforeEach(() => localStorage.setItem('tbp_session', '1'));
+beforeEach(() => {
+    localStorage.setItem('tbp_session', '1');
+    // jsdom has no canvas: the matrix preview renders, draws nothing.
+    vi.spyOn(HTMLCanvasElement.prototype, 'getContext').mockReturnValue(null);
+});
 afterEach(() => {
     cleanup();
     localStorage.clear();
@@ -65,6 +71,17 @@ describe('PointsPage', () => {
         expect(card('BANNER_BACKGROUND').querySelector('[data-effect="grid"]')).not.toBeNull();
     });
 
+    it('previews the new CSS and canvas looks without parallax listeners', async () => {
+        const add = vi.spyOn(window, 'addEventListener');
+        await renderPage();
+
+        const card = (slot) => screen.getByText(`POINTS.SLOTS.${slot}`).closest('[data-slot="card"]');
+        expect(card('PAGE_BACKGROUND').querySelector('[data-effect="snow"]')).not.toBeNull();
+        expect(card('BANNER_BACKGROUND').querySelector('[data-effect="matrix"] canvas')).not.toBeNull();
+        expect(add.mock.calls.filter(([type]) => type === 'pointermove')).toHaveLength(0);
+        add.mockRestore();
+    });
+
     it('shows a locked unlock item with its progress, a progress bar and no price or Buy button', async () => {
         await renderPage();