Bump Toto from 4 M to 22 M (small) — same data path, larger model

docs: document the hybrid cadence (5-min display, hourly inference)

Zoom view uses 5-min cadence (Ecowitt's actual storage granularity)

Document scoreboard methodology in-app and in the spec

Document Toto inference: full spec in docs/ + in-app footnote

Add Ecowitt API client and incremental SQLite archive