Adds generic child link support to ASTNode (addChild/setChild for multi/single-
valued roles, getChildren/getChild/allChildren for traversal). Function and
Variable as first child concepts of Module. Test builds Module->Function tree,
walks parent/child pointers in both directions, verifies single-valued replace.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Adds the C++ editor stack foundation with ASTNode (id, conceptType, parent pointer, virtual dtor) and Module as the first concrete concept (name, targetLanguage). Header-only, compiles with C++20, test passes all assertions.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
