fix(ui): D.2b-B — address phase-boundary review (burden % saturation + equipped filter)

Opus phase-boundary review findings:
- I1 (faithfulness): LoadToPercent now computes from the CLAMPED fill
  (floor(LoadToFill(load)*300)), so the burden % SATURATES at 300% like retail
  (decomp 176544-176576 clamps arg2 to [0,1] BEFORE the *300). The old
  floor(load*100) over-read to 400% at 4x capacity. Golden test corrected.
- I2 (partition): exclude equipped items (CurrentlyEquippedLocation != None) from
  the contents grid + selector — a mid-session self-wield routes them through
  MoveItem(item, WielderGuid=player) into GetContents(player); retail's gm3DItemsUI
  shows pack contents only. New conformance test.
- N1: drop dead 'using System.Collections.Generic' (left after the 383e8b7 cleanup).
- N3: AP-48 risk wording (drift can be low OR high vs server EncumbranceVal).

Build green; BurdenMath 17, InventoryController/UiMeter 10 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/AcDream.App.Tests/UI/Layout/InventoryControllerTests.cs

@@ -85,6 +85,24 @@ public class InventoryControllerTests
         Assert.Equal(0xCu, containers.GetItem(0)!.ItemId);
     }
 
+    [Fact]
+    public void Equipped_items_are_excluded_from_the_grid_and_selector()
+    {
+        var (layout, grid, containers, _, _, _, _, _) = BuildLayout();
+        var objects = new ClientObjectTable();
+        SeedContained(objects, 0xA, Player, slot: 0);                 // loose pack item
+        // A self-wielded item: MoveItem with an equip location indexes it under the player
+        // (the live wield path), but it must NOT show in the pack grid or the selector.
+        objects.AddOrUpdate(new ClientObject { ObjectId = 0xD });
+        objects.MoveItem(0xD, Player, newSlot: 1, newEquipLocation: EquipMask.MeleeWeapon);
+
+        Bind(layout, objects);
+
+        Assert.Equal(1, grid.GetNumUIItems());          // only the loose item
+        Assert.Equal(0xAu, grid.GetItem(0)!.ItemId);
+        Assert.Equal(0, containers.GetNumUIItems());    // equipped item is not a side bag either
+    }
+
     [Fact]
     public void Grid_is_six_columns_thirtytwo_px()
     {