feat(check): stub /check/check_time_slip_card_master_hash

Bare BaseTask call fired from DeckDecisionUI.cs:140 (Arena "View Deck"
path) and the TK2 prep screen. Client task has no Parse() override —
just checks result_code, ignores body. Prod (4 captured instances
across traffic_prod_taketwo_selections + traffic_prod_tradeables_capture)
unanimously responds with data: [].

Routing smoke added.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

SVSim.UnitTests/RoutingSmokeTests.cs

@@ -111,6 +111,7 @@ public class RoutingSmokeTests
     [TestCase("/arena_colosseum/get_fee_info")]
     [TestCase("/arena/get_challenge_info")]
     [TestCase("/arena/get_challenge_ranking_history")]
+    [TestCase("/check/check_time_slip_card_master_hash")]
     public async Task Authenticated_route_resolves(string path)
     {
         using var factory = new TestFactory();