oldIndex hardcoded to "1" for all modes

[mgordon79]

Bug: oldIndex hardcoded to "1" for all modes in Mode.payload()

Description

The Mode.payload() method hardcodes oldIndex to "1" for every mode, but the correct value differs per mode as shown in the comments of Client.set_mode():

# Time of use:      oldIndex=3
# Emergency Backup: oldIndex=1
# Self consumption: oldIndex=2

Impact

Sending the wrong oldIndex causes the FranklinWH app to no longer correctly display the current operating mode, even though the battery itself behaves correctly.

Suggested Fix

Each static factory method (time_of_use, emergency_backup, self_consumption) should set the correct oldIndex on the Mode instance, and payload() should use it:

def time_of_use(soc=20):
    mode = Mode(soc)
    mode.currendId = 9322
    mode.workMode = 1
    mode.oldIndex = 3
    return mode

def emergency_backup(soc=100):
    mode = Mode(soc)
    mode.currendId = 9324
    mode.workMode = 3
    mode.oldIndex = 1
    return mode

def self_consumption(soc=20):
    mode = Mode(soc)
    mode.currendId = 9323
    mode.workMode = 2
    mode.oldIndex = 2
    return mode