Boot reason via watchdog scratch register, reboot/picoboot CLI commands, enum msgpack support

lib/client/types.go

@@ -6,11 +6,30 @@ type RequestPICOBOOT struct{}
 type ResponsePICOBOOT struct{}
 
 type RequestInfo struct{}
+type BootReason uint8
+
+const (
+	BootCold    BootReason = 0
+	BootReboot  BootReason = 1
+)
+
+func (b BootReason) String() string {
+	switch b {
+	case BootCold:
+		return "cold"
+	case BootReboot:
+		return "reboot"
+	default:
+		return "unknown"
+	}
+}
+
 type ResponseInfo struct {
 	BoardID      [8]byte
 	MAC          [6]byte
 	IP           [4]byte
 	FirmwareName string
+	Boot         BootReason
 }
 
 type RequestLog struct{}