Fix Flask-Script integration

[neob91-close]

Importing tasktiger.flask_script blows up:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/src/tasktiger/flask_script.py", line 12, in <module>
    class TaskTigerCommand(Command):
  File "/src/tasktiger/flask_script.py", line 21, in TaskTigerCommand
    def __init__(self, tiger: TaskTiger) -> None:
NameError: name 'TaskTiger' is not defined

[neob91-close]

Also looks like we want to remove this entirely.

I know, but as long as it's still here, might as well not be broken. :)