LANTERN purge B6: delete the legacy single-ability path (sockets are THE ability model)

AbilityRef, AbilityCooldown, EffectiveAbilityStats, DefaultAbility deleted.
GoInGameServerSystem seeds the per-frame 4-socket Spark loadout UNCONDITIONALLY
(was gym-only); ClassSelectReceiveSystem + DebugOp.SetClass swap FrameId +
re-seed sockets + zero SocketCooldown; ClassSwapUtil.Apply drops newAbilityId;
EquipSystem weapons become stat-sticks (GrantedAbilityId removed from the item
blob/authoring); StatRecomputeSystem folds CharacterStatsRef + sockets only;
HUD cooldown bar reads socket 0 of SocketCooldown/EffectiveSocketStats; class
HUD readers are FrameId-only (ClassForAbility/AbilityFor deleted);
DebugModifierInjectionSystem drops CycleAbility.

390 tests green; Play-verified: a non-gym spawn gets frame=2 with Sparks
[7,8,6,9] and no console errors.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/_Project/Scripts/Client/Presentation/MetaShopHudSystem.cs

@@ -74,9 +74,9 @@ namespace ProjectM.Client
             // server-only); tiers from the replicated MetaTierState record on the director ghost.
             byte localClass = ClassTraits.WarriorClass;
             bool haveLocalPlayer = false;
-            foreach (var (fr, ar) in SystemAPI.Query<RefRO<FrameId>, RefRO<AbilityRef>>().WithAll<PlayerTag, GhostOwnerIsLocal>())
+            foreach (var fr in SystemAPI.Query<RefRO<FrameId>>().WithAll<PlayerTag, GhostOwnerIsLocal>())
             {
-                localClass = fr.ValueRO.Value != 0 ? fr.ValueRO.Value : ClassTraits.ClassForAbility(ar.ValueRO.Id); // FrameId signal, AbilityRef fallback
+                localClass = ClassTraits.Normalize(fr.ValueRO.Value); // FrameId is the sole class signal (legacy AbilityRef deleted)
                 haveLocalPlayer = true;
                 break;
             }