fix(core): wipe() with no arguments should clear all state instead of raising

[eeshsaxena]

What

State.wipe() with no arguments should clear all state, but currently raises TypeError.

The docstring says:

If you pass nothing in it will delete the whole thing.

But when both delete and keep are None, the method fell through to the keep branch and evaluated key not in keep with keep=None:

>>> from burr.core.state import State
>>> State({"a": 1, "b": 2}).wipe()
TypeError: argument of type 'NoneType' is not a container or iterable

The delete= and keep= forms were covered by tests, but the documented no-args form was not, so this went unnoticed.

Fix

Handle the three cases explicitly in wipe():

• delete=[...] -> delete those keys
• keep=[...] -> delete everything not kept
• neither -> delete every key (matches the docstring)

Verification

State({"a": 1, "b": 2}).wipe()            # {}
State({"a": 1, "b": 2}).wipe(keep=["a"])   # {"a": 1}
State({"a": 1, "b": 2}).wipe(delete=["a"]) # {"b": 2}

Added test_state_wipe_all alongside the existing wipe tests. tests/core/test_state.py passes (27 passed).