Fix remaining errcheck warnings in daemon.go, daemon_lock.go, delete.go

- daemon.go: fix os.Remove() in stopDaemon (line 602)
- daemon_lock.go: fix f.Close() and fmt.Fprintf() calls
- delete.go: fix cmd.Usage(), out.Close(), and os.Remove() calls

All error returns now properly handled or explicitly ignored.

Amp-Thread-ID: https://ampcode.com/threads/T-56b6d9f4-16a4-4c50-b7b9-dde1c3774650
Co-authored-by: Amp <amp@ampcode.com>

cmd/bd/daemon.go

@@ -599,7 +599,7 @@ func stopDaemon(pidFile string) {
 				fmt.Fprintf(os.Stderr, "Error killing process: %v\n", err)
 			}
 		}
-		os.Remove(pidFile)
+		_ = os.Remove(pidFile)
 		fmt.Println("Daemon killed")
 	}
 }