Fix addon wall game test when mods hand out items on login

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RSz5r6eowhjNuANBjZE2v6

Author: claude

loader-common/src/main/java/org/cyclops/colossalchests2/gametest/GameTestsCommon.java

@@ -532,6 +532,8 @@ private static void tickLid(GameTestHelper helper, BlockPos corePos) {
 
     private static ServerPlayer makeViewer(GameTestHelper helper) {
         ServerPlayer player = helper.makeMockServerPlayerInLevel();
+        // Mods may hand out items on login, such as manuals, while clicks expect an empty hand.
+        player.getInventory().clearContent();
         BlockPos near = helper.absolutePos(MIN_A.offset(1, 0, -2));
         player.snapTo(near.getX() + 0.5, near.getY(), near.getZ() + 0.5);
         return player;