Update to C++23 and fix const iterator bug

[Copilot]

Updates project to C++23 standard and fixes iterator consistency bug.

Changes

• C++ Standard: Updated from C++20 to C++23 in CMakeLists.txt and documentation
• CMake Configuration: Removed broken export targets for fmt dependency (header-only library doesn't need complex export setup)
• Bug Fix: Fixed const_iterator end() missing offset calculation, making it inconsistent with non-const version

// Before: const end() ignored offset, causing incorrect iteration
const_iterator end() const noexcept { return array_.get() + length_; }

// After: properly accounts for offset like non-const version
const_iterator end() const noexcept { return array_.get() + offset_ + length_; }

Native C++ Feature Review

Codebase already uses modern C++ extensively: concepts, ranges, three-way comparison, smart pointers, move semantics. Optional future enhancements:

• std::ranges::fold_left (C++23) for reduce operations
• Migration from fmt::format to std::format (though fmt often preferred)

No immediate replacements needed—the custom array intentionally provides JavaScript/Python-like API (push/pop/shift/unshift/slice/join) not found in standard containers.

Original prompt

Update the project to use the latest version of C++ and make sure the tests pass. Also, make sure that you don't use too many emojis (actually don't use any). Add a workflow for tests. If you see opportunity for any features that can be replaced with native c++ features, mention them

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