feat(data): offline name + measured-property enrichment

[rvnminers-A-and-N]

Precompute names + measured properties so the demo resolves instantly and offline.

Acceptance

• Pull common + IUPAC names + measured BP/VP from PubChem (public domain) into properties.parquet
• App reads a precomputed name table first (instant), live PubChem only as fallback
• Substitution / neighbor / palette reads show common + IUPAC + SMILES

Delivered by #74, #75, #81.

[rvnminers-A-and-N]

Shipped in #74, #75, #81.