fix(delegation): flush stdout before exit to prevent piped output truncation

console.log followed immediately by process.exit truncated piped output
at the pipe buffer (about 64 KiB) because stdout writes to pipes are
asynchronous. Interactive TTY runs were unaffected, so the bug only
surfaced for callers consuming ccs delegation output through a pipe,
such as scripts parsing --output-format json results from thinking
heavy GLM sessions.

Await an explicit stdout write callback before exiting in both route()
and _handleContinue().

src/delegation/delegation-handler.ts

@@ -35,6 +35,17 @@ function isFlag(arg: string): boolean {
   return arg.startsWith('-');
 }
 
+/**
+ * Write to stdout and wait for the flush to complete.
+ * process.exit() right after a large piped write truncates output at the
+ * pipe buffer (~64 KiB), so delegation results must be drained first.
+ */
+function writeStdoutAndFlush(text: string): Promise<void> {
+  return new Promise((resolve) => {
+    process.stdout.write(text + '\n', () => resolve());
+  });
+}
+
 function isInlineCcsValueFlag(arg: string): boolean {
   return Array.from(CCS_FLAGS_WITH_VALUE).some(
     (flag) => flag.startsWith('--') && arg.startsWith(`${flag}=`)
@@ -147,7 +158,7 @@ export class DelegationHandler {
 
       // 5. Format and display results
       const formatted = await ResultFormatter.format(result);
-      console.log(formatted);
+      await writeStdoutAndFlush(formatted);
 
       // 6. Exit with proper code
       process.exit(result.exitCode || 0);
@@ -192,7 +203,7 @@ export class DelegationHandler {
     });
 
     const formatted = await ResultFormatter.format(result);
-    console.log(formatted);
+    await writeStdoutAndFlush(formatted);
 
     process.exit(result.exitCode || 0);
   }