fix: stop sending port-in-use errors to Sentry (#558)

Port conflicts are expected — Chromium retries with a different port.
These errors were flooding Sentry (14k+ events) without user impact.

- handleStartupError: move Sentry.captureException below the
  port-in-use check so it only fires for unexpected startup errors
- handleControllerStartupError: skip Sentry capture for port errors
- index.ts: exit early for port errors before Sentry capture

packages/browseros-agent/apps/server/src/index.ts

@@ -20,6 +20,7 @@ import './lib/polyfill'
 import { EXIT_CODES } from '@browseros/shared/constants/exit-codes'
 import { CommanderError } from 'commander'
 import { loadServerConfig } from './config'
+import { isPortInUseError } from './lib/port-binding'
 import { Sentry } from './lib/sentry'
 import { Application } from './main'
 
@@ -39,6 +40,9 @@ try {
   if (error instanceof CommanderError) {
     process.exit(error.exitCode)
   }
+  if (isPortInUseError(error)) {
+    process.exit(EXIT_CODES.PORT_CONFLICT)
+  }
   Sentry.captureException(error)
   console.error('Failed to start server:', error)
   process.exit(EXIT_CODES.GENERAL_ERROR)

packages/browseros-agent/apps/server/src/main.ts

@@ -231,7 +231,6 @@ export class Application {
     console.error(
       `[FATAL] Failed to start ${serverName} on port ${port}: ${errorMsg}`,
     )
-    Sentry.captureException(error)
 
     if (isPortInUseError(error)) {
       console.error(
@@ -240,6 +239,7 @@ export class Application {
       process.exit(EXIT_CODES.PORT_CONFLICT)
     }
 
+    Sentry.captureException(error)
     process.exit(EXIT_CODES.GENERAL_ERROR)
   }
 
@@ -255,7 +255,9 @@ export class Application {
         { port },
       )
     }
-    Sentry.captureException(error)
+    if (!isPortInUseError(error)) {
+      Sentry.captureException(error)
+    }
   }
 
   private logStartupSummary(controllerServerStarted: boolean): void {