docs: install snapshot instead of a single file, so config.json is fetched too

docs: lead install instructions with the Hub-tracked download path

Add BatteryMHM preprint (PAPER.md + PDF); link from model card

metadata: enrich tags + add metrics and model-index for discoverability

docs: add 'How to use it' section (install + usage examples)

Polish model card: hook, badges, 30s quickstart, headline result

Open BatteryMHM method release (CC BY-NC 4.0, no weights)