feat: update backend OCR parser, web app, mobile app camera/preview UI, tests, and documentation with sample images

backend/nginx.conf

@@ -16,7 +16,7 @@ http {
 
     server {
         listen 80;
-        server_name localhost;
+        server_name _; # accept any host — tunnel URLs, IPs, custom domains
 
         # Disable body size limit for large image/pdf base64 payloads
         client_max_body_size 0;