feat(landing): implement mobile landing page with wallet deep-links (#4)

tests/landing.test.ts

@@ -0,0 +1,24 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import * as fs from 'fs';
+import * as path from 'path';
+
+describe('Mobile Landing Page (#4)', () => {
+  const htmlPath = path.join(__dirname, '../src/landing/mobile.html');
+  const html = fs.readFileSync(htmlPath, 'utf8');
+
+  it('includes wallet app deep-links for MetaMask, Coinbase Wallet, and Rainbow', () => {
+    assert.ok(html.includes('href="metamask://"'), 'MetaMask deep-link missing');
+    assert.ok(html.includes('href="cbwallet://"'), 'Coinbase Wallet deep-link missing');
+    assert.ok(html.includes('href="rainbow://"'), 'Rainbow deep-link missing');
+  });
+
+  it('tracks mobile_landing_cta_click conversion event', () => {
+    assert.ok(html.includes('mobile_landing_cta_click'), 'Conversion event tracking missing');
+  });
+
+  it('contains mobile viewport and responsive styles', () => {
+    assert.ok(html.includes('name="viewport"'), 'Viewport meta tag missing');
+    assert.ok(html.includes('@media (min-width: 600px)'), 'Responsive media query missing');
+  });
+});