build: complete the IWYU tail — APawn in VoxelWorld.cpp

VoxelWorld.cpp:526 dereferences the pawn, so APawn must be complete; Casts.h only
forward-declares it. Adds GameFramework/Pawn.h, and PlayerController.h which was
complete transitively only — the same fragility this change removes.

My earlier scan covered Public/ only. The shared PCH served .cpp files too, and
APawn was named in Build.cs's own error list. Everything else in the module
compiled, so this is the entire tail.

UNVERIFIED: not compiled.

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

Source/VoxelForge/VoxelForge.Build.cs

@@ -54,6 +54,8 @@ public class VoxelForge : ModuleRules
 		// it — never to revert FPSemantics, which is now load-bearing for cross-platform play.
 		// Headers fixed on 2026-07-27: VoxelBiomeDefinition, VoxelSettings, VoxelStrateDefinition,
 		// VoxelStrateTypes, VoxelContentManager, VoxelAtmosphereManager, VoxelDensityVolume.
+		// Plus VoxelWorld.cpp (GameFramework/Pawn.h) — the .cpp files needed auditing too, not just
+		// the public headers. That was the whole residual tail: one site, found in one build.
 		// Expect a residual tail: the shared PCH hid these for years and only a build enumerates
 		// them all. VoxelDensityVolume's was the nasty one — ENABLE_DRAW_DEBUG is used in an #if,
 		// and an undefined macro there is silently 0 rather than an error.