fix: Settings panel now respects NEXT_PUBLIC_GATEWAY_URL (#468)

The multi-gateway panel was constructing WebSocket URLs client-side
using buildGatewayWebSocketUrl() with the gateway's DB host/port,
ignoring the server-side URL resolution that respects
NEXT_PUBLIC_GATEWAY_URL, Tailscale Serve, and reverse-proxy configs.

- Remove client-side buildGatewayWebSocketUrl fallback in connectTo()
  — server's /api/gateways/connect already handles all URL resolution
- Simplify gatewayMatchesConnection() to use direct host/port string
  matching without constructing a derived WS URL
- Remove unused buildGatewayWebSocketUrl import

Fixes #468

src/components/panels/multi-gateway-panel.tsx

@@ -5,7 +5,6 @@ import { useTranslations } from 'next-intl'
 import { Button } from '@/components/ui/button'
 import { useMissionControl } from '@/store'
 import { useWebSocket } from '@/lib/websocket'
-import { buildGatewayWebSocketUrl } from '@/lib/gateway-url'
 
 interface Gateway {
   id: number
@@ -130,19 +129,11 @@ export function MultiGatewayPanel() {
     const normalizedConn = url.toLowerCase()
     const normalizedHost = String(gw.host || '').toLowerCase()
 
-    if (normalizedHost && normalizedConn.includes(normalizedHost)) return true
+    // Skip localhost matching — server rewrites localhost to browser hostname,
+    // so the connection URL won't contain "127.0.0.1". Port matching handles it.
+    if (normalizedHost && normalizedHost !== '127.0.0.1' && normalizedHost !== 'localhost' && normalizedConn.includes(normalizedHost)) return true
     if (normalizedConn.includes(`:${gw.port}`)) return true
-
+    return false
-    try {
-      const derivedWs = buildGatewayWebSocketUrl({
-        host: gw.host,
-        port: gw.port,
-        browserProtocol: window.location.protocol,
-      }).toLowerCase()
-      return normalizedConn.includes(derivedWs)
-    } catch {
-      return false
-    }
   }, [connection.url])
 
   const shouldShowConnectionSummary =
@@ -179,11 +170,10 @@ export function MultiGatewayPanel() {
       if (!res.ok) return
       const payload = await res.json()
 
-      const wsUrl = String(payload?.ws_url || buildGatewayWebSocketUrl({
+      // Use server-resolved URL only — it respects NEXT_PUBLIC_GATEWAY_URL,
-        host: gw.host,
+      // Tailscale Serve, and reverse-proxy configurations.
-        port: gw.port,
+      const wsUrl = payload?.ws_url
-        browserProtocol: window.location.protocol,
+      if (!wsUrl) return
-      }))
       const token = String(payload?.token || '')
       connect(wsUrl, token)
     } catch {