fix(server): remove debug logging and add error handling from review

- Remove debug log.Printf calls from handler/daemon.go and service/task.go
  that used the global log package instead of structured logging
- Remove unused truncate() helper from service/task.go
- Add error handling for EnqueueTaskForIssue in createAgentInitIssue
- Clean up verbose debug logging in daemon/daemon.go handleTask
- Add shutdown sequence comment to codex.go lifecycle goroutine

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/pkg/agent/codex.go

@@ -104,7 +104,10 @@ func (b *codexBackend) Execute(ctx context.Context, prompt string, opts ExecOpti
 		c.closeAllPending(fmt.Errorf("codex process exited"))
 	}()
 
-	// Drive the session lifecycle in a goroutine
+	// Drive the session lifecycle in a goroutine.
+	// Shutdown sequence: lifecycle goroutine closes stdin + cancels context →
+	// codex process exits → reader goroutine's scanner.Scan() returns false →
+	// readerDone closes → lifecycle goroutine collects final output and sends Result.
 	go func() {
 		defer cancel()
 		defer close(msgCh)