fix(lighting): #143 — dynamic lights use retail's D3D 1/d attenuation (portal + viewer spread)

The portal swirl's magenta light (and the viewer fill) read as a tight,
concentrated pool vs retail's soft, room-wide tint. Cause: acdream applied its
STATIC dat-bake falloff (1/d^3 distance-cube + range x1.3) to ALL point lights,
including dynamic ones. Retail draws dynamic lights through the D3D hardware
path (config_hardware_light 0x0059ad30): a point light gets Attenuation1=1 =>
att = 1/d (inverse-linear), plain Lambert, range x1.5 (rangeAdjust 0x00820cc4).

Split the two paths by a per-light IsDynamic flag:
- LightSource.IsDynamic; packed into GlobalLight.coneAngleEtc.y (binding=4).
- LightInfoLoader.Load(isDynamic) => range x1.5 + flag (server-object/portal
  lights via the live spawn path); dat-static lights keep x1.3 (default).
- Viewer fill + weenie/portal lights = dynamic; dat torches = static.
- mesh_modern.vert pointContribution: dynamic branch = 1/d att, plain Lambert,
  hard cutoff, no per-light cap (D3D accumulates then saturates via the existing
  min(pointAcc,1)); static branch = the unchanged wrap/norm bake.

This is the portal half of #143 (the magenta light itself now registers + reaches
the walls via the prior weenie-light + landblock-key fix). Refines AP-35: point
lights now split static-bake (1/d^3) vs dynamic-hardware (1/d) by path.

Verified: portal light now range=9 (6x1.5), magenta spreads softly; shader
compiles clean; static torches unchanged (range 5.2/6.5/7.8). User-confirmed the
portal matches retail and the torch-lit interior did not over-brighten.
Core lighting 44/44, App 476 green.

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

src/AcDream.Core/Lighting/LightSource.cs

@@ -47,6 +47,8 @@ public sealed class LightSource
     public float     ConeAngle = 0f;  // radians, Spot only
     public uint      OwnerId;         // attached entity id; 0 = world-global
     public bool      IsLit = true;    // SetLightHook latch
+    public bool      IsDynamic;       // #143: true = D3D hardware path (1/d att, range×1.5);
+                                      // false = static dat-baked bake (1/d³, range×1.3)
 
     // Cached each frame by LightManager.
     public float DistSq;