chore: sync ISO build configs with live server state

- Add nginx snippets (PWA, HTTPS app proxies) to image-recipe/configs/
- Update build script Dockerfile to install openssl, generate self-signed
  SSL cert, copy nginx snippets, and create Cloud dummy directories
- Ensures fresh ISO installs have working HTTPS, PWA installability,
  and pre-created Cloud storage folders

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

image-recipe/configs/snippets/archipelago-pwa.conf

@@ -0,0 +1,16 @@
+# PWA installability - required for Install (not just Add to Home Screen) on Android
+# Manifest MUST be served with application/manifest+json - Chrome rejects otherwise
+location = /manifest.webmanifest {
+    default_type application/manifest+json;
+    add_header Cache-Control "public, max-age=0, must-revalidate";
+}
+# Service worker - no cache so updates apply
+location ~ ^/(sw\.js|workbox-.*\.js|registerSW\.js)$ {
+    add_header Content-Type application/javascript;
+    add_header Service-Worker-Allowed /;
+    add_header Cache-Control "no-cache, no-store, must-revalidate";
+}
+# index.html - avoid aggressive cache for PWA updates
+location = /index.html {
+    add_header Cache-Control "public, max-age=0, must-revalidate";
+}