feat(headless): Add GhostObjectManagerDummy for headless mode

[bobtista]

Depends on #2137 (ParticleSystem use-after-free fix) to avoid crash during headless replay playback.

Summary

• Add GhostObjectManagerDummy class that stubs out ghost object operations for headless mode
• Set it up to be instantiated when TheGlobalData->m_headless is true
• Based on Helmut's work in [ZH] Implement Headless Mode #651

Testing

• Run with -headless -replay <file> and verify no crashes (cherry pick the particlesystem fix first)

Todo

• Replicate to Generals

Notes

-I tried to add InGameUIDummy too, but it broke things.
-The GhostObjectManagerDummy overrides only the operational methods (reset, addGhostObject, removeGhostObject, etc.) while inheriting crc/xfer/loadPostProcess from the base class to maintain save/load compatibility.

[greptile-apps]

Greptile Summary

Added GhostObjectManagerDummy class to stub out ghost object operations for headless mode, enabling replay playback without graphics rendering.

• Created GhostObjectManagerDummy that inherits from GhostObjectManager and overrides operational methods (reset, addGhostObject, removeGhostObject, etc.) to do nothing
• Modified W3DGameLogic::createGhostObjectManager() to instantiate GhostObjectManagerDummy when TheGlobalData->m_headless is true
• The dummy implementation correctly inherits crc/xfer/loadPostProcess from base class to maintain save/load compatibility (avoiding the W3DGhostObjectManager implementation that expects non-null ghost objects)
• All callers of addGhostObject properly handle nullptr returns, making the stub implementation safe
• Uses nullptr (not NULL) following the project's C++ coding standard

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• The implementation is architecturally sound - GhostObjectManagerDummy correctly stubs out ghost object operations for headless mode while preserving save/load compatibility by inheriting the base class serialization methods. All callers properly handle nullptr returns from addGhostObject. The code follows existing patterns from PR [ZH] Implement Headless Mode #651 and has been tested with headless replay playback. The use of nullptr instead of NULL follows the custom rule.
• No files require special attention

Important Files Changed

Filename	Overview
GeneralsMD/Code/GameEngine/Include/GameLogic/GhostObject.h	Added GhostObjectManagerDummy class that stubs out ghost object operations for headless mode while preserving save/load compatibility
GeneralsMD/Code/GameEngineDevice/Include/W3DDevice/GameLogic/W3DGameLogic.h	Modified createGhostObjectManager to return GhostObjectManagerDummy when in headless mode, otherwise W3DGhostObjectManager

Sequence Diagram

sequenceDiagram
    participant GameLogic
    participant W3DGameLogic
    participant TheGlobalData
    participant GhostObjectManagerDummy
    participant W3DGhostObjectManager
    participant PartitionData
    
    GameLogic->>W3DGameLogic: createGhostObjectManager()
    W3DGameLogic->>TheGlobalData: check m_headless flag
    
    alt Headless Mode
        W3DGameLogic->>GhostObjectManagerDummy: NEW GhostObjectManagerDummy
        GhostObjectManagerDummy-->>GameLogic: return (as GhostObjectManager*)
        Note over GhostObjectManagerDummy: All operations stubbed out<br/>Returns nullptr from addGhostObject
    else Normal Mode
        W3DGameLogic->>W3DGhostObjectManager: NEW W3DGhostObjectManager
        W3DGhostObjectManager-->>GameLogic: return
        Note over W3DGhostObjectManager: Full implementation<br/>Creates W3DGhostObject instances
    end
    
    Note over GameLogic: Later during gameplay...
    PartitionData->>GameLogic: TheGhostObjectManager->addGhostObject(obj, pd)
    
    alt Headless Mode
        GameLogic->>GhostObjectManagerDummy: addGhostObject(obj, pd)
        GhostObjectManagerDummy-->>PartitionData: return nullptr
        Note over PartitionData: m_ghostObject = nullptr<br/>All subsequent uses check for null
    else Normal Mode
        GameLogic->>W3DGhostObjectManager: addGhostObject(obj, pd)
        W3DGhostObjectManager-->>PartitionData: return W3DGhostObject*
        Note over PartitionData: m_ghostObject = valid pointer<br/>Used for fog-of-war rendering
    end

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[greptile-apps]

_{4 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

style: unnecessary static_cast since GhostObjectManagerDummy already inherits from GhostObjectManager

Suggested change

	virtual GhostObjectManager *createGhostObjectManager(void) { return TheGlobalData->m_headless ? static_cast<GhostObjectManager*>(NEW GhostObjectManagerDummy) : NEW W3DGhostObjectManager; }
	virtual GhostObjectManager *createGhostObjectManager(void) { return TheGlobalData->m_headless ? NEW GhostObjectManagerDummy : NEW W3DGhostObjectManager; }

_{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

Prompt To Fix With AI

This is a comment left during a code review.
Path: GeneralsMD/Code/GameEngineDevice/Include/W3DDevice/GameLogic/W3DGameLogic.h
Line: 64:64

Comment:
**style:** unnecessary `static_cast` since `GhostObjectManagerDummy` already inherits from `GhostObjectManager`

```suggestion
	virtual GhostObjectManager *createGhostObjectManager(void) { return TheGlobalData->m_headless ? NEW GhostObjectManagerDummy : NEW W3DGhostObjectManager; }
```

<sub>Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!</sub>

How can I resolve this? If you propose a fix, please make it concise.

[bobtista]

I think this is required for VC6, it failed to build without it

[helmutbuhler]

Did you add this for performance reasons, or to reduce headless checks? I don't see any removed headless checks.