Adds EXIF date extraction during indexing so photos can be sorted by when
they were actually taken, not just when the file was modified on disk.
- Add `taken_at` (nullable TEXT, ISO 8601) column to the images table via
ensure_column migration and a new idx_images_taken_at index
- Populate taken_at in build_record via extract_exif_date, which tries
DateTimeOriginal → DateTimeDigitized → DateTime tags and rejects all-zero
sentinel dates written by uninitialised cameras
- upsert_image uses taken_at = excluded.taken_at so a re-indexed file gets
fresh EXIF; stale dates from replaced files are not preserved
- Add taken_asc / taken_desc sort using COALESCE(taken_at, created_at) so
images without EXIF gracefully fall back to their creation date
- Surface as "Taken: newest / oldest" in the Toolbar sort dropdown
- Shift map_image_row column indices after the new taken_at (index 10)
LyAhn
9ee5b08c93