Fix the southward migration: explore direction had a hardcoded +Y bias

Root cause of towns (East worst) drifting south: when an exploring soul was
at its anchor with no outward vector, the fallback direction was
Vector2(PersonalityModifier, 1 - Abs(PersonalityModifier)) - and with
PersonalityModifier tiny (+-0.2) that Y-component was always ~+0.9. +Y is
south, so every town's explorers got shoved into the southern corner. East
showed it worst (selfish souls strip resources fastest, so they explore
most). Now the at-anchor direction comes from the soul's identity hash,
spread around the full compass.

Supporting fixes: exploration is bounded to a ~140-unit home range (forage
out and back, don't march to the horizon); private homesteads clamp to
within 120 units of the town anchor (selfish souls sprawl on their OWN
land, not into a neighbor's). Result: every East home now founds near the
east anchor (x~870 vs the anchor's 962), none in South's territory, and
East is the healthiest town.

Also widened the map view (880 -> 1060px) to use more of the window - the
world grew to 1152 but the render was a fixed square, so it looked no bigger.

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

scripts/Visualization.cs

@@ -14,10 +14,10 @@ public partial class Visualization : Node2D
 
     // Layout: 1600×900 window — map fills the left square, panel the right.
     private const float MapOffset = 10f;
-    private const float MapPixels = 880f;
-    private const float CellPixels = MapPixels / World.GridSize;   // ~3.44
-    private const float PanelX = 910f;
-    private const float PanelWidth = 680f;
+    private const float MapPixels = 1060f;   // fills most of the 1600px window
+    private const float CellPixels = MapPixels / World.GridSize;
+    private const float PanelX = 1085f;
+    private const float PanelWidth = 505f;
 
     private static readonly Color PanelBg   = new(0.10f, 0.10f, 0.12f);
     private static readonly Color MapBg     = new(0.13f, 0.13f, 0.15f);