--free returns chargers whose fee is unknown

[galjos]

--free is documented as "only chargers explicitly free (fee=no)" (cli.py:108), but the filter is:

if free_only and st.fee is True:   # chargers.py:223
    continue

That drops only fee=True. fee=None — the OSM tag is absent — passes through and is presented as free.

Measured within 25 km of Bolzano today:

fee	stations
None (unknown)	86
True	65
False	21

--free returns 107, of which 21 are actually fee=no. An 80% false-positive rate on a filter whose whole purpose is to exclude paid chargers, and the direction is the harmful one: a user filters for free and is sent to a charger that may bill them.

Fix

if free_only and st.fee is not False: continue, so the filter means what the help says.

Worth checking --public at chargers.py for the same shape while there.

Done when

• --free returns only fee=False.
• A test covers all three values, including None.