Implement copy constructors

A legacy asset container currently relies on the default shallow copy and leaks GPU handles when duplicated. Implement a copy constructor for Mesh that performs deep copy of vertex buffers and duplicates GPU references correctly, leaves both objects usable, and documents the cost. Add unit tests that copy a mesh and then destroy the original to confirm the copy remains valid. Ladder L1

Before I add explicit copy constructors for resource classes, prepare the change to make reviewers comfortable. Show which members need deep copy versus shared ownership, put the expensive operations and their costs up front, and flag places where copying should be prohibited instead of copied. Ladder L2

A crash happened when two Mesh instances, one copied from the other, were destroyed; I suspect the copy constructor performed a shallow copy of the GPU handle. I cannot tell whether other code depends on copy semantics being deep. What is the likely root cause and the safest immediate fix to prevent double-free, and how to audit other copies in the codebase? Ladder L5

Historically the codebase lets heavy resource objects be implicitly copyable, causing crashes and performance issues as teams duplicate meshes or textures without thinking. What habit should we change across the team: should we make resource types non-copyable by default, document copy costs, add tooling or linters to detect accidental copies, and how to migrate existing code with minimal churn? Ladder L6