Implement Memory Pool for Fixed-Size Objects

Implement memory pool for fixed-size objects with O(1) allocation/deallocation.

Requirements:

• Define MemoryPool structure with memory block, free list, metadata
• Implement pool_create(size, capacity) to initialize pool
• Implement pool_alloc(pool) to allocate block (O(1))
• Implement pool_free(pool, ptr) to free block (O(1))
• Implement pool_destroy(pool) to cleanup
• Track free_count and validate operations
• Demonstrate 10-20x speedup over malloc/free
• Show usage example with many allocations
• Handle out-of-memory condition gracefully
• Print pool statistics and comparison