FIX: Add READY status to saturn_printer.py

[TehDizzy]

Couple of recommended tweaks:

1: No active prints return the following when "cassini.py status" is executed:

E:\Programs\Python Scripts\cassini-main>python cassini.py status
192.168.xxx.xxx:
    Saturn3Ultra (ELEGOO Saturn 3 Ultra)
    Machine Status: READY
Traceback (most recent call last):
  File "E:\Programs\Python Scripts\cassini-main\cassini.py", line 188, in <module>
    main()
  File "E:\Programs\Python Scripts\cassini-main\cassini.py", line 171, in main
    do_status(printers)
  File "E:\Programs\Python Scripts\cassini-main\cassini.py", line 61, in do_status
    print(f"    Print Status: {PrintInfoStatus(print_info['Status']).name}")
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.496.0_x64__qbz5n2kfra8p0\Lib\enum.py", line 744, in __call__
    return cls.__new__(cls, value)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.12_3.12.496.0_x64__qbz5n2kfra8p0\Lib\enum.py", line 1158, in __new__
    raise ve_exc
ValueError: 0 is not a valid PrintInfoStatus

The fix is to add "READY = 0" to the class PrintInfoStatus:

# Status field inside PrintInfo
class PrintInfoStatus(Enum):
    # TODO: double check these
    READY = 0
    EXPOSURE = 2 
    RETRACTING = 3
    LOWERING = 4
    COMPLETE = 16 # pretty sure this is correct

As shown below:

E:\Programs\Python Scripts\cassini-main>python cassini.py status
192.168.xxx.xxx:
    Saturn3Ultra (ELEGOO Saturn 3 Ultra)
    Machine Status: READY
    Print Status: READY
    Layers: 0/0
    File:
    File Transfer Status: IDLE

2: File Transfer Status shows ERROR when no print is active:

E:\Programs\Python Scripts\cassini-main>python cassini.py status
192.168.xxx.xxx:
    Saturn3Ultra (ELEGOO Saturn 3 Ultra)
    Machine Status: READY
    Print Status: IDLE
    Layers: 0/0
    File:
    File Transfer Status: ERROR

The fix is to rename "ERROR = 3" to "IDLE = 3" in the class FileStatus in saturn_printer.py to more accurately describe the printer's state:

# Status field inside FileTransferInfo
class FileStatus(Enum):
    NONE = 0
    DONE = 2
    IDLE = 3

As shown below:

E:\Programs\Python Scripts\cassini-main>python cassini.py status
192.168.xxx.xxx:
    Saturn3Ultra (ELEGOO Saturn 3 Ultra)
    Machine Status: READY
    Print Status: READY
    Layers: 0/0
    File:
    File Transfer Status: IDLE