Serve /api/ws without Basic auth so the live feed connects

Browsers don't reliably replay Basic-auth credentials on a WebSocket upgrade,
so the dashboard's live feed was stuck on "reconnecting" (only the 5s REST
poll worked). Give /api/ws a higher-priority Traefik router that skips Basic
auth; the backend still requires API_TOKEN, which nginx injects on the
handshake. The deploy now fails closed unless CRYPTO_API_TOKEN is set.

Also: split the nginx /api/ws block so upgrade headers are only set there, and
add reconnect backoff (2s -> 30s) so a failing socket stops hammering.

frontend/nginx.conf

@@ -8,7 +8,10 @@ server {
         try_files $uri $uri/ /index.html;
     }
 
-    location /api/ {
+    # WebSocket feed. Kept in its own block so the upgrade headers are only set
+    # here, and so the API token is injected server-side on the handshake (the
+    # browser cannot set headers on a WebSocket).
+    location /api/ws {
         proxy_pass http://backend:8000;
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
@@ -16,6 +19,16 @@ server {
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_read_timeout 3600s;
+        proxy_send_timeout 3600s;
+        proxy_set_header ${API_TOKEN_HEADER} "${API_TOKEN}";
+    }
+
+    location /api/ {
+        proxy_pass http://backend:8000;
+        proxy_http_version 1.1;
+        proxy_set_header Host $host;
+        proxy_set_header X-Real-IP $remote_addr;
+        proxy_read_timeout 3600s;
         # Inject the optional API token server-side so the browser never sees it
         # and the WebUI keeps working without any client changes.
         proxy_set_header ${API_TOKEN_HEADER} "${API_TOKEN}";

frontend/src/api.js

@@ -25,17 +25,32 @@ export const deletePreset = (id) => http.delete(`/presets/${id}`).then((r) => r.
 
 export function openSocket({ onMessage, onOpen, onClose }) {
   const proto = window.location.protocol === 'https:' ? 'wss' : 'ws'
+  const url = `${proto}://${window.location.host}/api/ws`
   let socket
   let retryTimer
   let closed = false
+  let attempt = 0
+
+  const schedule = () => {
+    if (closed) return
+    // Back off from 2s up to 30s so a persistently failing socket (e.g. auth)
+    // does not hammer the server, while a brief blip still reconnects fast.
+    const delay = Math.min(2000 * 2 ** attempt, 30000)
+    attempt += 1
+    retryTimer = setTimeout(connect, delay)
+  }
 
   const connect = () => {
-    socket = new WebSocket(`${proto}://${window.location.host}/api/ws`)
-    socket.onopen = () => onOpen?.()
+    if (closed) return
+    socket = new WebSocket(url)
+    socket.onopen = () => {
+      attempt = 0
+      onOpen?.()
+    }
     socket.onmessage = (event) => onMessage?.(JSON.parse(event.data))
     socket.onclose = () => {
       onClose?.()
-      if (!closed) retryTimer = setTimeout(connect, 2000)
+      schedule()
     }
     socket.onerror = () => socket.close()
   }