Add offline page, navigation preload, page cache, and pwa:create:sw commands

- Create /offline route and neo-brutalist offline page with retry button
- Add navigation_preload: true for faster SW navigation
- Add page_cache: 50 entries, 24h, 3s network timeout
- Add pwa_dev/pwa_prod Makefile commands using pwa:create:sw

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config/packages/pwa.yaml

@@ -77,6 +77,7 @@ pwa:
         scope: /
         use_cache: false
         skip_waiting: true
+        navigation_preload: true
         workbox:
             cache_manifest: true
             image_cache:
@@ -91,6 +92,11 @@ pwa:
             asset_cache:
                 enabled: true
                 regex: '/\.(css|jsx?)$/'
+            page_cache:
+                enabled: true
+                max_entries: 50
+                max_age: 86400
+                network_timeout: 3
     favicons:
         enabled: true
         default: