catalog: add generated v3 JAXB binding and ex-2 test data

The ex-2 schema describes a nested Guess-Market/GM-events document in
which every event carries its pricing mechanism inline, as either a
GM-LMSR element holding the liquidity parameter b or a GM-order-book
element holding the allow-mint, initial and d attributes, instead of
naming a mechanism and passing its parameters separately.

Add the xjc-generated classes for that schema under catalog.model.v3,
along with the fixtures the loader will be tested against: small.xml
with two events, one per mechanism, multiple.xml with four, and two
negative cases -- error-2.xml, where a market maker is funded with
zero initial cash, and error-3.xml, where a market maker points at
event id 12, which no event declares -- so the cross-reference and
funding checks have something to reject.

The binding covers the GM-events subtree only. The GM-users half of
the document and the per-event id element are not bound yet, so
nothing reads these classes so far.

0 files changed, 0 insertions, 0 deletions