feat: integrate COS and unify user persistence

deploy/nginx-file.conf.example

@@ -0,0 +1,11 @@
+# Include this location in the server block for 101.43.139.56.
+# Preserve /file/access and the token query when forwarding.
+location /file/ {
+    proxy_pass http://127.0.0.1:8080;
+    proxy_set_header Host $host;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+    # File tokens are temporary credentials; omit query strings from access logs.
+    access_log off;
+}