fix(native-chat): make the structured close-failure toast provider-neutral

The structuredSessionCloseFailed toast fires for any structured session,
but its copy said 'Codex chat', so a Claude structured session that fails
to close showed the wrong provider name. The launch-failure toast is only
reachable behind the agent === 'codex' gate, so its copy stays as is.

Claude-Session: https://claude.ai/code/session_013ugSpCx4AWkySaJb69BQax

src/renderer/src/components/tab-group/useTabGroupTabCloseCommands.ts

@@ -17,7 +17,7 @@ function reportStructuredSessionCloseError(error: unknown): void {
   toast.error(
     translate(
       'components.native-chat.structuredSessionCloseFailed',
-      'Could not close this Codex chat'
+      'Could not close this chat session'
     ),
     { description: error instanceof Error ? error.message : String(error) }
   )

src/renderer/src/components/terminal/terminal-tab-actions.ts

@@ -157,7 +157,7 @@ export function closeTerminalTab(
         toast.error(
           translate(
             'components.native-chat.structuredSessionCloseFailed',
-            'Could not close this Codex chat'
+            'Could not close this chat session'
           ),
           {
             description: translate(

src/renderer/src/i18n/locales/en.json

@@ -16707,7 +16707,7 @@
         "message": "Structured Chat blocks terminal prompts and sends. Orchestration messages remain queued; switch to Terminal, then check the Orca inbox with",
         "command": "orca orchestration check"
       },
-      "structuredSessionCloseFailed": "Could not close this Codex chat",
+      "structuredSessionCloseFailed": "Could not close this chat session",
       "structuredSessionLaunchFailed": "Could not open Codex chat",
       "structuredSessionCloseFailedDescription": "The terminal stayed open so the provider remains recoverable.",
       "handoff": {