fix(tui): revert "fix(core): handle SIGHUP and kill process (#16057)"

This reverts commit 45ac20b8aa1c96751af6824bf7dd736554ef7938.

packages/opencode/src/index.ts

@@ -46,11 +46,6 @@ process.on("uncaughtException", (e) => {
   })
 })
 
-// Ensure the process exits on terminal hangup (eg. closing the terminal tab).
-// Without this, long-running commands like `serve` block on a never-resolving
-// promise and survive as orphaned processes.
-process.on("SIGHUP", () => process.exit())
-
 let cli = yargs(hideBin(process.argv))
   .parserConfiguration({ "populate--": true })
   .scriptName("opencode")