Apply PR #18527: fix(core): restore SIGHUP exit handler (#16057)

Author: opencode-agent[bot]

packages/opencode/src/cli/cmd/tui/context/exit.tsx

@@ -53,6 +53,7 @@ export const { use: useExit, provider: ExitProvider } = createSimpleContext({
         message: store,
       },
     )
+    process.on("SIGHUP", () => exit())
     return exit
   },
 })