Cut 6: wire StatSource.PowerSupply and refuse a power request that reads it

docs/stats-and-power-cut.md Cut 6, purely additive per its own map: the enum member, the
resolver's generation-cache and the bus's PowerSupply write already existed (Cuts 2/3/5)
as an identity everywhere. This lands the two things Cut 6 actually adds.

The curve: EquippedItem.PowerSupplyFactor now returns pow(PowerSupply, exponent) instead
of the Cut-3 identity stub, so a stat that declares a PowerSupply term degrades as this
tick's grant falls and reads unchanged at full supply (pow(1, n) == 1 regardless of n).
PowerBus.AllocateTiers now invalidates StatSource.PowerSupply once per draw per tick -- the
missing half of the wiring named in the cut map -- so the resolver actually recomputes when
the grant moves, using the same per-source generation scheme Heat/Durability already use
(unconditional, at most once per tick, never touching a stat that did not declare the
source).

The request-independence rule: a stat that decides a power request may not depend on power
supply, directly or through a modifier chain. Direct dependency is checked statically
(StatValidation.ValidateNoPowerSupplyOnRequest, ItemData.cs) against a fixed registry of
(BehaviorData type, field) pairs -- the one PerformanceStat each IPowerConsumer's own
PowerRequest evaluates as its request, a compile-time fact rather than something authored
per instance -- and runs at catalog load (AetheriaStores.Open), at Upsert, and again at
equip (EquippedItem's constructor) as defense against the two named bypasses that write a
catalog document without going through Upsert. The modifier-chain half is dynamic
(StatModifier.ValidateNoPowerSupplyChain): a modifier's own magnitude stat is walked
through the same magnitude->target edges ValidateNoCycle already builds for the self-cycle
check, and refused at Initialize (equip time) if it is power-tainted and targets a known
request stat, naming both items.

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

Assets/Scripts/ServerShared/Entity.cs

@@ -1354,6 +1354,14 @@ public class EquippedItem : IStatContext
             if (consumerTiers.Length > 0)
                 EquippableItem.PowerTier = consumerTiers.Min();
         }
+
+        // Cut 6 (docs/stats-and-power-cut.md): "the validator runs at catalog load, at Studio save, and at
+        // equip." AetheriaStores.Open/CultRecordRefs.Upsert already refuse this at catalog write time; re-running
+        // the same static check here is what closes the gap for the two named bypasses (CultCache Studio's
+        // generic editor, AetherDb's dangling-ref apply) rather than silently trusting that every catalog on disk
+        // went through Upsert. The modifier-chain half of the rule is dynamic (it depends on what is actually
+        // equipped alongside this item) and lives in StatModifier.Initialize instead.
+        StatValidation.ValidateNoPowerSupplyOnRequest(Data.Name, Data.Behaviors);
     }
 
     // Cut 2 (docs/stats-and-power-cut.md): the resolver owns the value; this is the caller's read of it, keyed by
@@ -1363,13 +1371,18 @@ public class EquippedItem : IStatContext
     public float HeatFactor(float exponent) => pow(ThermalPerformance, ThermalExponent * exponent);
     public float DurabilityFactor(float exponent) => pow(DurabilityPerformance, DurabilityExponent * exponent);
     public float ConsumableProgressFactor(float exponent) => 1f;
-    public float PowerSupplyFactor(float exponent) => 1f;
+    // Cut 6 (docs/stats-and-power-cut.md): the brownout curve. A stat with a PowerSupply term degrades as this
+    // tick's grant falls below 1 and is exactly unchanged at full supply (pow(1, exponent) == 1 regardless of
+    // exponent) -- the operator's "a continuous consumer that degrades instead of stopping." PowerBus writes
+    // PowerSupply below; the resolver invalidates this source once per tick from the same write (PowerBus.cs
+    // AllocateTiers), so this read is always this tick's own grant, never a stale one.
+    public float PowerSupplyFactor(float exponent) => pow(PowerSupply, exponent);
 
     // Cut 3 (docs/stats-and-power-cut.md §1.2): PowerBus's grant ratio for this item, in [0,1], from whichever
-    // tick last ran its Step. Display-only and (once Cut 6 wires StatSource.PowerSupply into the resolver)
-    // stat-source-only: the only other reader is the very IPowerConsumer behaviour that declared the request this
-    // reflects. Forbidden writers: nothing but PowerBus sets this. Defaults to 1 (fully supplied) for an item
-    // that draws no power, or before the bus has run once.
+    // tick last ran its Step. Display-only and, as of Cut 6, stat-source-only: the only other reader is the
+    // resolver, through PowerSupplyFactor above, on behalf of whichever IPowerConsumer behaviour declared a
+    // PowerSupply term. Forbidden writers: nothing but PowerBus sets this. Defaults to 1 (fully supplied) for an
+    // item that draws no power, or before the bus has run once.
     public float PowerSupply { get; internal set; } = 1f;
 
     // Cut 2: these used to read the catalog stat's own per-entity dictionary (the leak, §0.3). A modifier now