Capture pre-grant npm download baseline; commit to docs/program/

[dlrice]

Context
Historical NPM package download data exists and is the natural pre-grant adoption baseline.

Scope
Pull historical download data for protvista-uniprot from the public npm registry API (https://api.npmjs.org/downloads/range/{period}/protvista-uniprot; no auth required; data goes back to early 2015, package published from 2018).

Commit docs/program/npm-baseline.md containing:

• Annual download totals from 2018 through end of Q1 (30 Apr 2026).
• Monthly download series for the last 24 months, for trend visibility.
• The exact API calls used and the pull date.
• A short paragraph on the soft-rename (protvista-uniprot → protvista with v5) and how forward metrics will reconcile across the two package names once v5 ships.

Reference the baseline file in the Q2 progress report's "Software-usage metrics" section.

Acceptance

• docs/program/npm-baseline.md committed to main.
• Pull date and data cutoff stated explicitly in the file header.
• Forward-metric reconciliation note included.
• Q2 report references the file in section 6.3 (or equivalent).