probe: gate grand-exchange-live, the first interactive environment

Eight environments gated, one warning left (tera-crow-nav). The probe calls
measure_ladder.ladder() rather than re-deriving the policies, and seeds from the
skip-aware baskets() helper — a contiguous range() grades a different set of
baskets than the model is served.

Beyond the four-rung ladder it asserts what house rule 4 actually claims: the
turn budget binds in every block of twenty-four, sweeps all 64 cells of the
reference family, scans the rendered turns for held-out ticks, and checks that
hostile replies parse to a hold and score zero.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/test_probe.py

@@ -21,7 +21,6 @@ ROW = re.compile(r"^(?P<name>\S(?:.*\S)?)\s{2,}(?:-?\d+\.\d+\s*){4}\s+(?P<verdic
 #
 # It only ever shrinks. Delete a name here in the same commit that lands its probe.
 PENDING_PROBES = frozenset({
-    "grand-exchange-live",
     "tera-crow-nav",
     "tera-drive-101",
     "tera-office-nav",