Fix clang-tidy readability-identifier-naming violations

[Copilot]

Renames identifiers across core graph node and registration code to satisfy the repository's readability-identifier-naming clang-tidy rules (lowercase for most identifiers, CamelCase for template parameters).

Changes

• declared_fold.hpp: r → result_type (type alias); expand using result_type = std::decay_t<...> per reviewer suggestion; fix incomplete rename that left make_type_ids<r>() and std::unique_ptr<r> referencing an undeclared type
• simple_ptr_map.hpp: Rename try_emplace parameter ptr → node_ptr to eliminate ptr ptr shadowing of the nested type alias
• registrar.hpp: Rename constructor parameter nodes → node_map to eliminate nodes& nodes shadowing of the nested type alias
• Transform/predicate/observer/unfold/fold nodes: Template parameters N/M → num_inputs/num_outputs (single-letter names were flagged as too short and unclear)
• CMakeLists.txt: Remove ENABLE_CLANG_TIDY option; update CLANG_TIDY_CONFIGURATION.md to reflect direct use of CMAKE_CXX_CLANG_TIDY

Example: parameter shadowing fixes

// Before
explicit registrar(nodes& nodes, ...);          // 'nodes' shadows type alias
auto try_emplace(std::string node_name, ptr ptr); // 'ptr' shadows type alias

// After
explicit registrar(nodes& node_map, ...);
auto try_emplace(std::string node_name, ptr node_ptr);

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[Copilot]

Pull request overview

This PR focuses on resolving clang-tidy readability-identifier-naming issues by renaming identifiers (notably to avoid parameter/type alias shadowing) in Phlex’s core registration plumbing.

Changes:

• Renamed the registrar constructor parameter from nodes to node_map to avoid nodes& nodes shadowing the nested using nodes = ... alias.