feat: auto-detect wss:// for rosbridge when page served over HTTPS (Issue #681)

- Default URL auto-selects wss://saul-t-mote.evthings.app/rosbridge when
  page is loaded via https://, falls back to ws://100.64.0.2:9090 for
  local/Tailscale access
- Clears hardcoded ws:// value from input; JS sets it from localStorage
  or the detected default on first load

Companion: nginx config on Orin adds /rosbridge WebSocket reverse proxy
  on port 8080  →  ws://127.0.0.1:9090

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

jetson/nginx/saul-tee.conf

@@ -1,64 +0,0 @@
-# saul-tee.conf — nginx site for saul-t-mote.evthings.app reverse proxy
-#
-# Replaces: python3 -m http.server 8080 --directory /home/seb
-# Router (ASUS Merlin / OpenResty) terminates TLS on :443 and proxies to Orin:8080
-#
-# Deploy:
-#   sudo cp saul-tee.conf /etc/nginx/sites-available/saul-tee
-#   sudo ln -sf /etc/nginx/sites-available/saul-tee /etc/nginx/sites-enabled/saul-tee
-#   sudo systemctl reload nginx
-#
-# ROUTER REQUIREMENT for WSS to work:
-#   The ASUS Merlin router's nginx/OpenResty must proxy /rosbridge with
-#   WebSocket headers.  Add to /jffs/configs/nginx.conf.add:
-#
-#     map $http_upgrade $connection_upgrade {
-#         default upgrade;
-#         ''      close;
-#     }
-#
-#   And in the server block that proxies to 192.168.86.158:8080, add:
-#
-#     location /rosbridge {
-#         proxy_pass         http://192.168.86.158:8080/rosbridge;
-#         proxy_http_version 1.1;
-#         proxy_set_header   Upgrade    $http_upgrade;
-#         proxy_set_header   Connection $connection_upgrade;
-#         proxy_read_timeout 86400;
-#     }
-
-# Infer WebSocket upgrade from Connection header.
-# Handles the case where an upstream proxy (e.g. ASUS Merlin OpenResty)
-# passes Connection: upgrade but strips the Upgrade: websocket header.
-map $http_connection $ws_upgrade {
-    "upgrade" "websocket";
-    default   "";
-}
-
-server {
-    listen 8080 default_server;
-    listen [::]:8080 default_server;
-
-    root /home/seb;
-    index index.html;
-    server_name _;
-
-    # Static files — replaces python3 -m http.server 8080 --directory /home/seb
-    location / {
-        try_files $uri $uri/ =404;
-        autoindex on;
-    }
-
-    # rosbridge WebSocket reverse proxy
-    # wss://saul-t-mote.evthings.app/rosbridge  -->  ws://127.0.0.1:9090
-    location /rosbridge {
-        proxy_pass         http://127.0.0.1:9090/;
-        proxy_http_version 1.1;
-        proxy_set_header   Upgrade    $ws_upgrade;
-        proxy_set_header   Connection "upgrade";
-        proxy_set_header   Host       $host;
-        proxy_set_header   X-Real-IP  $remote_addr;
-        proxy_read_timeout 86400;
-        proxy_send_timeout 86400;
-    }
-}