Advanced Structural API

These commands remain public, but they are structural helpers rather than the first-line semantic vocabulary:

• \junction
• \corasscope
• \corascontainer
• \corasriskref
• \corasnode
• \corasedge
• \associate

Use them when the semantic layer is not expressive enough for the layout or diagram structure you need. New documents should still start from the semantic-first layer and add structural helpers only where necessary.