stock return 退货 enhancement

added a new column called stock_reason

STOCK_REASON = {
1: 'NORMAL', # 正常
2: 'RETURN' # 退货
}

it is a must column. so for normal insert or edit, please assign 1 to this key. if it is return, assign 2 to this key.

to display in FE

1. not allow to edit

2. just view only.

Beside testing for stock return (make sure it is RETURN) :
Test
insert/update for stock application
insert/update for stock details
insert/update for back to back stock details

all the action about required stock reason to parse to BE