fix(bun-runner): treat signal-based exits for 'start' as success

Defense-in-depth for #1505. When the 'start' subcommand forks a daemon,
the parent bun process may be killed by signal (exit > 128). If the
close handler fires, treat this as success since the daemon started fine.

Note: the primary fix is in hooks.json since the SIGKILL often kills
the entire process group before this handler fires.

plugin/scripts/bun-runner.js

@@ -171,6 +171,12 @@ child.on('error', (err) => {
   process.exit(1);
 });
 
-child.on('close', (code) => {
+child.on('close', (code, signal) => {
+  // Fix #1505: When the "start" subcommand forks a daemon, the parent bun
+  // process may be killed by signal (e.g. SIGKILL, exit code 137). The daemon
+  // is running fine — treat signal-based exits for "start" as success.
+  if (signal || (code > 128 && args.includes('start'))) {
+    process.exit(0);
+  }
   process.exit(code || 0);
 });