Initial commit: bt411 -- standalone Windows BattleTech (Tesla 4.10 port)

Clean, self-contained extraction of the BattleTech-specific work from the
reverse-engineering workspace -- engine + game + content + build, with nothing
from Red Planet or the raw archive dumps. Builds green (Win32) and runs the
single-player drive->animate->target->fire->damage->destroy loop out of the box.

Layout:
  engine/   MUNGA + MUNGA_L4 shared 2007 engine, carrying our BT render/loader
            work (bgfload/L4D3D/L4VIDEO: BSL bit-slice decode, LOD/ground/shadow
            models) + image codec; the minimal rp/ headers the audio HAL needs
  game/     reconstructed BT logic + surviving-original BT source + fwd shims
            + WinMain launcher
  content/  full runtime tree (BTL4.RES, VIDEO/, GAUGE/, AUDIO/, eggs, BTDPL.INI)
  docs/     format specs + reconstruction ledgers
  reference/ raw Ghidra pseudocode (recon source-of-truth) + decomp exporter
  tools/    MP console emulator + map/resource scanners

One top-level CMake builds munga_engine lib + bt410_l4 game lib + btl4.exe.
All paths relativized (186 fwd shims + ~437 CMake abs paths -> repo-relative);
DXSDK is the one external, overridable via -DDXSDK. Verified: builds to a
byte-identical 2.27MB exe and runs combat (TARGET DESTROYED, 0 crashes) against
the bundled content.

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

engine/rp/DEMOPACK.h

@@ -0,0 +1,121 @@
+#pragma once
+
+#include "rivet.h"
+
+struct DemolitionPack__ModelResource :
+	public Rivet::ModelResource
+{
+	Scalar
+		blastRadiusSquared;
+	Scalar
+		detectionRadiusSquared;
+	Scalar
+		fuseTime;
+	Scalar
+		concussiveForce;
+};
+
+//##########################################################################
+//####################    DemolitionPack       #############################
+//##########################################################################
+
+class DemolitionPack :
+	public Rivet
+{
+public:
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Shared Data support
+//
+public:
+	static Derivation *GetClassDerivations();
+	static SharedData DefaultData;
+
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Attribute Support
+//
+#if 0
+public:
+	enum {
+		NextAttributeID
+	};
+
+private:
+	static const IndexEntry AttributePointers[];
+
+protected:
+	//static AttributeIndexSet	AttributeIndex
+	static AttributeIndexSet& GetAttributeIndex();
+#endif
+
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Model support
+//
+public:
+	enum {
+		DefaultFlags = Mover::DefaultFlags|NoCollisionTestFlag
+	};
+
+	typedef void (DemolitionPack::*Performance)(Scalar time_slice);
+
+	void
+		SetPerformance(Performance performance)
+			{
+				Check(this);
+				activePerformance = (Simulation::Performance)performance;
+			}
+
+	void
+		MoveAndHunt(Scalar time_slice);
+	void
+		Hunt(Scalar time_slice);
+	void
+		ProcessCollision(
+			Scalar time_slice,
+			BoxedSolidCollision &collision,
+			const Point3D &old_position,
+			Damage *damage
+		);
+
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Construction and Destruction
+//
+public:
+	typedef DemolitionPack__ModelResource ModelResource;
+	 
+	static DemolitionPack*
+		Make(MakeMessage *creation_message);
+
+	DemolitionPack(
+		MakeMessage *creation_message,
+		SharedData &virtual_data = DefaultData
+	);
+	~DemolitionPack();
+
+	Logical
+  	TestInstance() const;
+
+static int
+	CreateModelResource(
+		ResourceFile *resource_file,
+		const char *model_name,
+		NotationFile *model_file,
+		const ResourceDirectories *directories,
+		ModelResource* model = NULL
+	);
+
+//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+// Local Data
+//
+public:
+	Scalar
+		blastRadiusSquared;
+
+	Scalar
+		detectionRadiusSquared;
+
+	Scalar
+		fuseTime;
+
+	Scalar
+		concussiveForce;
+};