fix: enhance gateway logging for Windows dev restart debugging (#665)

Add comprehensive debug logging throughout the gateway lifecycle to
help troubleshoot nodemon restart issues on Windows, where SIGTERM
is used instead of SIGUSR2.

Changes:
- Enhanced shutdown handler to log all signals and env var states
- Gateway manager now logs process detachment mode explicitly
- Added environment variable confirmation on bootstrap
- Updated gateway-development.md with new debug logs and troubleshooting steps

Benefits:
- Easier troubleshooting of gateway lifecycle issues
- Clear visibility into signal handling during nodemon restarts
- Better cross-platform development experience
- Production behavior remains unchanged

Testing:
- ✅ Windows: Gateways persist across nodemon restarts
- ✅ macOS/Linux: Existing SIGUSR2 behavior preserved
- ✅ Production: Default shutdown cleanup unchanged
- ✅ Backward compatibility: No breaking changes

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/server/src/services/hermes/gateway-manager.ts

@@ -148,8 +148,18 @@ function isLocalHost(host: string): boolean {
 }
 
 function shouldDetachGatewayProcess(): boolean {
+  // In dev mode (nodemon), always detach gateway processes so they survive restarts
+  // Production mode: attach gateways so they can be managed together with the server
   const override = process.env.HERMES_WEB_UI_STOP_GATEWAYS_ON_SHUTDOWN?.trim().toLowerCase()
-  return override === '0' || override === 'false'
+  const shouldDetach = override === '0' || override === 'false'
+
+  if (shouldDetach) {
+    console.log('[gateway] Detaching gateway process (dev mode: HERMES_WEB_UI_STOP_GATEWAYS_ON_SHUTDOWN=' + override + ')')
+  } else {
+    console.log('[gateway] Attaching gateway process (prod mode: HERMES_WEB_UI_STOP_GATEWAYS_ON_SHUTDOWN=' + (override || 'not set') + ')')
+  }
+
+  return shouldDetach
 }
 
 // ============================