Fix golangci-lint errcheck and unused errors

- manager.go: add _ = to syscall.Kill and proc.Signal calls (6 fixes)
- chat.go: add _ = to c.Writer.WriteString calls (9 fixes)
- webhook.go: remove unused webhookSecret field

internal/llama/manager.go

@@ -92,14 +92,14 @@ func (m *Manager) Stop() {
 
 		pgid, err := syscall.Getpgid(m.proc.Process.Pid)
 		if err == nil {
-			syscall.Kill(-pgid, syscall.SIGTERM)
+			_ = syscall.Kill(-pgid, syscall.SIGTERM)
 		} else {
-			m.proc.Process.Signal(syscall.SIGTERM)
+			_ = m.proc.Process.Signal(syscall.SIGTERM)
 		}
 
 		<-ctx.Done()
 		if m.proc.ProcessState == nil {
-			syscall.Kill(-pgid, syscall.SIGKILL)
+			_ = syscall.Kill(-pgid, syscall.SIGKILL)
 		}
 	}
 
@@ -256,9 +256,9 @@ func (m *Manager) terminateProcess() {
 
 	pgid, err := syscall.Getpgid(m.proc.Process.Pid)
 	if err == nil {
-		syscall.Kill(-pgid, syscall.SIGTERM)
+		_ = syscall.Kill(-pgid, syscall.SIGTERM)
 	} else {
-		m.proc.Process.Signal(syscall.SIGTERM)
+		_ = m.proc.Process.Signal(syscall.SIGTERM)
 	}
 
 	done := make(chan error, 1)
@@ -269,7 +269,7 @@ func (m *Manager) terminateProcess() {
 	select {
 	case <-ctx.Done():
 		if pgid, err := syscall.Getpgid(m.proc.Process.Pid); err == nil {
-			syscall.Kill(-pgid, syscall.SIGKILL)
+			_ = syscall.Kill(-pgid, syscall.SIGKILL)
 		}
 	case <-done:
 	}