Add local-first SPA architecture and containerized production deploy.

Move data access to use-cases and IndexedDB repositories with optional
remote fallback, changelog/sync ports, and encrypted local backup.
Add production Docker Compose (nginx frontend + optional backend) and
Apache host proxy configuration for deployment.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/nginx.conf

@@ -0,0 +1,20 @@
+server {
+    listen 80;
+    server_name _;
+
+    root /usr/share/nginx/html;
+    index index.html;
+
+    gzip on;
+    gzip_types text/css application/javascript application/json image/svg+xml;
+
+    location / {
+        try_files $uri $uri/ /index.html;
+    }
+
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff2?)$ {
+        expires 7d;
+        add_header Cache-Control "public, immutable";
+        try_files $uri =404;
+    }
+}