fix: add free-list to WardenEmulator heap allocator to prevent exhaustion

The bump-pointer allocator never reused freed blocks, causing the 16 MB
emulated heap to exhaust in long sessions even when blocks were freed.

- First-fit reuse from a free-list before advancing the bump pointer
- Coalesce adjacent free blocks to limit fragmentation
- Roll back the bump pointer when the top free block reaches it
- Reset allocator state on initialize() so re-runs start clean

include/game/warden_emulator.hpp

@@ -152,6 +152,7 @@ private:
 
     // Memory allocation tracking
     std::map<uint32_t, size_t> allocations_;
+    std::map<uint32_t, size_t> freeBlocks_;  // free-list keyed by base address
     uint32_t nextHeapAddr_;
 
     // Hook handles for cleanup