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/client/src/api/hermes/gateways.ts

@@ -0,0 +1,29 @@
+import { request } from '../client'
+
+export interface GatewayStatus {
+  profile: string
+  port: number
+  host: string
+  url: string
+  running: boolean
+  pid?: number
+}
+
+export async function fetchGateways(): Promise<GatewayStatus[]> {
+  const res = await request<{ gateways: GatewayStatus[] }>('/api/hermes/gateways')
+  return res.gateways
+}
+
+export async function startGateway(name: string): Promise<GatewayStatus> {
+  const res = await request<{ success: boolean; gateway: GatewayStatus }>(`/api/hermes/gateways/${name}/start`, { method: 'POST' })
+  return res.gateway
+}
+
+export async function stopGateway(name: string): Promise<void> {
+  await request(`/api/hermes/gateways/${name}/stop`, { method: 'POST' })
+}
+
+export async function checkGatewayHealth(name: string): Promise<GatewayStatus> {
+  const res = await request<{ gateway: GatewayStatus }>(`/api/hermes/gateways/${name}/health`)
+  return res.gateway
+}