fix(immich): prevent client SocketTimeoutException on large uploads

Add missing nginx directives recommended by Immich docs for mobile
photo backup over slow links:

- http2 on: multiplex parallel asset uploads from the mobile app
- client_body_timeout / send_timeout / keepalive_timeout 600s: cover
  the client<->nginx leg (default 60s matched the Android timeout)
- proxy_request_buffering off + proxy_buffering off: stream upload
  bytes to immich as they arrive instead of buffering the whole file,
  keeping the TCP connection active and avoiding idle-socket timeouts
- proxy_connect_timeout 600s: explicit upstream connect timeout

roles/immich/templates/nginx-vhost.conf.j2

@@ -20,6 +20,7 @@ server {
 server {
     listen 443 ssl;
     listen [::]:443 ssl;
+    http2 on;
     server_name {{ immich_nginx_hostname }};
 
     # Let's Encrypt certificates (managed by Certbot)
@@ -40,6 +41,12 @@ server {
 
     client_max_body_size 50000M;
 
+    # Timeouts for slow mobile uploads (client <-> nginx leg)
+    client_body_timeout 600s;
+    client_header_timeout 600s;
+    send_timeout 600s;
+    keepalive_timeout 600s;
+
     location / {
         proxy_pass http://127.0.0.1:{{ immich_port }};
         proxy_set_header Host $http_host;
@@ -52,7 +59,12 @@ server {
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection "upgrade";
 
-        # Timeouts for large file uploads
+        # Stream uploads directly to backend instead of buffering full body on disk
+        proxy_request_buffering off;
+        proxy_buffering off;
+
+        # Timeouts for large file uploads (nginx <-> immich leg)
+        proxy_connect_timeout 600s;
         proxy_read_timeout 600s;
         proxy_send_timeout 600s;
     }