Hot fix lookup

[Crazy-Rich-Meghan]

1. Changed m_points and m_data in gsLookupFunctionSingle to hold references instead of copies, reducing unnecessary data duplication.
2. Changed the Container typedef in gsLookupFunction to use memory::unique_ptr for storing Piece_t objects
3. Update pointer by using reset()

[Copilot]

Pull Request Overview

This PR refactors gsLookupFunction to use unique_ptr for Piece_t storage, updates cloning to handle pointer semantics, and changes gsLookupFunctionSingle to hold references for points and data.

• Switched Container to std::vector<memory::unique_ptr<Piece_t>>
• Implemented deep-copy clone() via clone_impl()
• Updated add(), set(), and evaluation methods to work with pointers
• Changed m_points and m_data in gsLookupFunctionSingle to references

Comments suppressed due to low confidence (2)

gsLookupFunction.h:158

• [nitpick] The comment references shared_ptr even though it isn’t used elsewhere. Clarify why unique_ptr is chosen (e.g., ownership semantics) or remove the shared_ptr mention.

        // Use unique_ptr - more efficient than shared_ptr

gsLookupFunction.h:326

• [nitpick] Holding m_points as a reference risks dangling references if the original matrices go out of scope. Consider using an owning type (shared_ptr/unique_ptr) or ensure callers manage the source lifetime.

    const gsMatrix<T>& m_points;