periodOf keyed a week by the Monday's YYYY-MM-DD, which collides with
the day-key form. Weeks now key as YYYY-Www (ISO 8601, e.g. 2025-W32);
the week-year comes from the week's Thursday, so it stays correct across
the January/December boundary. The Monday-start boundary and startsAt
are unchanged. Week tests now assert the ISO form.
Model: opus-4-8
TDD red phase for issue #44: the in-process read API served from RAM —
lib.albums (list/byName/byID), lib.photos (byID/records), Album/Photo
wrappers, and lib.timeline.groups with the PhotoFilter and day/week/month
grouping rules. These fail until src/library/read.ts lands.
Model: opus-4-8
sneak