Turns a SMILES into a readable chemical description rather than a table of
numbers. Useful for reports, for captioning a drawn structure, and for
checking that a structure is what you meant to draw.

style="human"     — compact, chemistry-facing narrative: the parent skeleton,
                    heteroatom positions, unsaturation, the principal
                    characteristic group, then substituents with their locants.
style="technical"  — the full naming walkthrough, including how the name was
                    assembled token by token.

Returns: `{name, paragraphs: [...], text, rules_hit, smiles, style, engine}`,
or `{error, smiles}`. `text` is the paragraphs joined for direct display.