feat: Add PWA assets and metadata for iOS Safari installation

- Generate app icons in multiple sizes (192x192, 512x512, 180x180, 32x32)
- Create favicon and apple-touch-icon SVG files
- Add comprehensive PWA meta tags in app layout
- Configure theme color (#3B82F6) and background color
- Update manifest.json with icon references (PNG and SVG)
- Create icon generation scripts (SVG and PNG conversion)
- Add browser-based PNG icon generator (HTML)
- Create comprehensive PWA testing guide
- Add icon setup documentation

Requirements: 4.1, 4.2
Task: 13. Add PWA assets and metadata

public/manifest.json

@@ -10,17 +10,29 @@
   "theme_color": "#3B82F6",
   "categories": ["productivity", "utilities"],
   "icons": [
+    {
+      "src": "/icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
     {
       "src": "/icon-192.svg",
       "sizes": "192x192",
       "type": "image/svg+xml",
-      "purpose": "any maskable"
+      "purpose": "any"
     },
     {
       "src": "/icon-512.svg",
       "sizes": "512x512",
       "type": "image/svg+xml",
-      "purpose": "any maskable"
+      "purpose": "any"
     }
   ],
   "screenshots": [],