fix(B.7): square indicator box + bigger pick sphere for doors/lifestones/portals + diag

Visual test surfaced three follow-ups:

1. Square box, not 1:2 rectangle.
   WidthHeightRatio: 0.5 → 1.0. Retail's Vivid Target Indicator draws
   a square; the earlier humanoid-aspect ratio looked wrong for
   non-humanoids and didn't match retail screenshots.

2. Large flat objects (doors / lifestones / portals / corpses)
   weren't selectable with the new tight 0.7 m pick sphere.
   WorldPicker.Pick now takes an optional radiusForGuid callback so
   the host can per-entity decide a larger radius. GameWindow's pick
   site supplies a lambda that bumps to 2.0 m for any entity with
   BF_DOOR (0x1000), BF_LIFESTONE (0x4000), BF_PORTAL (0x40000), or
   BF_CORPSE (0x2000) set in ObjectDescriptionFlags. Default stays
   at 0.7 m for humanoids and items.

3. New [B.7] pick-info diagnostic on each successful pick:
     [B.7] pick-info guid=0x... itemType=0x... pwd=0x... color=(r,g,b)
   Lets us verify e.g. whether a 'green NPC' really is server-side
   flagged as Vendor (BF_VENDOR=0x200, retail-defined green) vs a
   bug in our colour lookup. The pwd bit table is acclient.h:6431-
   6463 — same flags retail's gmRadarUI::GetBlipColor branches on.

Note: textured retail-sprite corner triangles remain a B.7 follow-up
deferred per the spec. MVP uses procedural fills.

src/AcDream.App/UI/TargetIndicatorPanel.cs

@@ -65,10 +65,12 @@ public sealed class TargetIndicatorPanel
 
     /// <summary>
     /// Box width = <see cref="EntityHeight"/> projected height ×
-    /// <see cref="WidthHeightRatio"/>. Humanoids are about half as
-    /// wide as tall on screen, so 0.5 is a sensible default.
+    /// <see cref="WidthHeightRatio"/>. Retail's Vivid Target Indicator
+    /// draws a square box — four corner triangles arranged in a square —
+    /// so 1.0 = width matches height. The earlier 0.5 (humanoid-ish
+    /// aspect) made the box uncomfortably narrow for non-humanoids.
     /// </summary>
-    public float WidthHeightRatio { get; set; } = 0.5f;
+    public float WidthHeightRatio { get; set; } = 1.0f;
 
     /// <summary>
     /// Floor for the projected screen height (pixels). Prevents the