feat: Add PWA support

- PWA_MOBILE_SPEC.md documentation
- manifest.json with app metadata
- Service Worker with caching strategies
- Offline page
- PWA registration in layout
- App icons (placeholder)

apps/web/public/icons/generate-icons.js

@@ -0,0 +1,61 @@
+const fs = require('fs');
+const { createCanvas } = require('canvas');
+
+function generateIcon(size, filename) {
+  const canvas = createCanvas(size, size);
+  const ctx = canvas.getContext('2d');
+  
+  // Background
+  ctx.fillStyle = '#0f172a';
+  ctx.beginPath();
+  ctx.roundRect(0, 0, size, size, size * 0.18);
+  ctx.fill();
+  
+  // Gradient for sparkle
+  const gradient = ctx.createLinearGradient(0, 0, size, size);
+  gradient.addColorStop(0, '#22d3ee');
+  gradient.addColorStop(1, '#3b82f6');
+  
+  // Draw sparkle
+  const cx = size / 2;
+  const cy = size / 2;
+  const s = size * 0.23; // sparkle size
+  
+  ctx.fillStyle = gradient;
+  ctx.beginPath();
+  ctx.moveTo(cx, cy - s);
+  ctx.lineTo(cx + s * 0.12, cy - s * 0.12);
+  ctx.lineTo(cx + s, cy);
+  ctx.lineTo(cx + s * 0.12, cy + s * 0.12);
+  ctx.lineTo(cx, cy + s);
+  ctx.lineTo(cx - s * 0.12, cy + s * 0.12);
+  ctx.lineTo(cx - s, cy);
+  ctx.lineTo(cx - s * 0.12, cy - s * 0.12);
+  ctx.closePath();
+  ctx.fill();
+  
+  // Small sparkles
+  ctx.fillStyle = '#22d3ee';
+  ctx.globalAlpha = 0.7;
+  ctx.beginPath();
+  ctx.arc(cx + size * 0.15, cy - size * 0.15, size * 0.023, 0, Math.PI * 2);
+  ctx.fill();
+  
+  ctx.fillStyle = '#3b82f6';
+  ctx.globalAlpha = 0.6;
+  ctx.beginPath();
+  ctx.arc(cx - size * 0.14, cy + size * 0.14, size * 0.015, 0, Math.PI * 2);
+  ctx.fill();
+  
+  const buffer = canvas.toBuffer('image/png');
+  fs.writeFileSync(filename, buffer);
+  console.log(`Generated ${filename}`);
+}
+
+try {
+  generateIcon(192, 'icon-192x192.png');
+  generateIcon(512, 'icon-512x512.png');
+  generateIcon(180, 'apple-touch-icon.png');
+} catch (e) {
+  console.error('Error:', e.message);
+}