v0.39.2 — fix: 1h history view clipped at the 15-min-data boundary

Fix (#144): the 1h Usage history chart capped its right edge at the date 15-min recording began (e.g. Jun 7), hiding the most recent week of hourly data.

Root cause was order-of-operations: the 1h view consumed the downsampled all-grain feed and reconciled on the client, so downsampling turned recent 15-min rows into lone slots that reconcileToHourly's "partial 15-min + no hourly → skip" rule discarded.

New server-side ?grain=1h path reconciles raw rows → hourly first, then downsamples (symmetric with ?grain=15m). Legacy 'all' feed unchanged. Display-only — no /api/verify / billed-number surface touched. 830 tests pass (+6, incl. a regression on the ordering).