A Takeout photo with no sidecar and no date in its name was filed under
the day of the import, and the app dated uploads by modification time.
A new `exiftime` module reads DateTimeOriginal (then DateTimeDigitized)
with its offset. Takeout uses it for undated photos it copies out for a
thumbnail, and the daemon uses it for app uploads before falling back to
the modification time (B244).
Each photo was ranked against every sidecar in its folder, so a folder
of 10,000 photos took about 30 s to scan. The sidecars are now indexed
by stem and each photo is ranked only against the stems a few range
lookups return: 0.1 s for the same folder, with the same matches (B235).
The prefix rule for sidecars whose names Google cut at 51 characters also
matched names that were never cut, so IMG_1.jpg's sidecar gave its title
and date to an IMG_12.jpg that had none. It now applies only to a sidecar
name at the cap. Edited copies, which have no sidecar of their own, take
their original's date by a rule of their own and keep their own name
(B225).
User-visible strings, doc comments and docs now say "Favorite" and
"color", matching the `pdfs favorite` command; UI_UX_PLAN.md §8 records
the choice. The changelog's 1.11.x and Unreleased entries said schema 30,
but V31 (`photos.resolved_at`) shipped in 1.11.0. Adds the missing
release links for 1.10.0 to 1.11.1.