nx_connect_events_lib.nx

nx_connect_events_lib.nx -- the real-world EVENTS + RSVP engine, extracted as a shared library so the verifying gate (nx_connect_events) and the LIVE app (nx_connect_serve /events) bind ONE implementation. Until this split the live page ran a hand-written admission check with NO CAPACITY AT ALL -- an event could be RSVP'd without limit, while this gate-proven engine sat unused. Symbols are moved VERBATIM, deliberately un-renamed: renaming is what silently de-grounded three rows of the public compare scorecard on the earlier splits (seq689), since matrix rows are verified by an implementing-symbol on disk. connect.matrix's events row was repointed at THIS file in the same change. ADMISSION ORDER IS LOAD-BEARING: membership, then idempotency, then the categorical youth wall, and only THEN capacity. Checking capacity first would let a nearly-full event become the reason a safety rule was skipped. Age is FAIL-CLOSED: a user with no verified band counts as a MINOR, so safety defaults down. RSVP codes: 1 admitted; 2 already-in (idempotent); -1 not a group member; -2 full; -3 two-deep denied; -4 minor on a non-youth event. license_tier: ORIGINAL