feat: add multi-gateway management with auto port detection

- Add GatewayManager for multi-profile gateway lifecycle management
- Auto-detect running gateways on startup via PID + health check
- Port conflict detection: check managed gateways, allocated ports, and
  system-level port availability (TCP bind test)
- Two-phase startup: sequential port resolution, parallel process launch
- Use `gateway start/restart` on normal systems, `gateway run --replace`
  on WSL/Docker
- Wait for health check before returning start/stop responses
- Add Gateways page with card-based layout showing profile status
- Reorganize sidebar navigation into collapsible groups
- Hide API server settings (now auto-managed by GatewayManager)
- Profile switch reloads page; Ctrl+C no longer stops gateways
- Remove redundant ensureApiServerConfig from index.ts and profiles.ts

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

packages/server/src/routes/hermes/proxy-handler.ts

@@ -1,5 +1,6 @@
 import type { Context } from 'koa'
 import { config } from '../../config'
+import { getGatewayManager } from './gateways'
 
 function isTransientGatewayError(err: any): boolean {
   const msg = String(err?.message || '')
@@ -27,8 +28,24 @@ async function waitForGatewayReady(upstream: string, timeoutMs: number = 5000):
   return false
 }
 
+/** Resolve upstream URL for a request based on profile header/query */
+function resolveUpstream(ctx: Context): string {
+  const mgr = getGatewayManager()
+  if (mgr) {
+    // Check X-Hermes-Profile header or ?profile= query param
+    const profile = ctx.get('x-hermes-profile') || (ctx.query.profile as string)
+    if (profile) {
+      return mgr.getUpstream(profile)
+    }
+    // Default to active profile's upstream
+    return mgr.getUpstream()
+  }
+  // Fallback: static upstream from config
+  return config.upstream.replace(/\/$/, '')
+}
+
 export async function proxy(ctx: Context) {
-  const upstream = config.upstream.replace(/\/$/, '')
+  const upstream = resolveUpstream(ctx)
   // Rewrite path for upstream gateway:
   //   /api/hermes/v1/* -> /v1/*  (upstream uses /v1/ prefix)
   //   /api/hermes/*     -> /api/* (upstream uses /api/ prefix)