Why not just make a new wall neer the brick one, from 2*3, just like a
partition wall.

'Free-standing frame: I would prefer other options before if only
because it's more work! It would also take more space'


put horizontal wood strips onto wall, just like sole and header
plates, but then attach the uprights differently. Put them onto the
_front_ face of the top and bottom pieces, instead of between them.
Probably as clear as mud... heres a sideways-on view then:
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NT