Add album view and bulk actions to Review

The Review list can now be grouped by album (disc folders folded in),
showing per-album counts of upgrades, identical files, downgrades and
approximate matches. Whole albums or individual songs can be selected and
linked, promoted, ignored or un-ignored in one action.

Every bulk action is previewed server-side first: how many songs will be
processed, which are skipped and why, and warnings with examples for
downgrades, approximate matches, duration mismatches, folder moves and
renames. Downgrades are excluded unless explicitly included, and
replacing master files requires an acknowledgement. Link and promote run
as a background job that re-plans each song and uses the normal
single-item operation, so all preflight checks still apply. IDs from
another pair are refused and duplicates are ignored.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -57,6 +57,13 @@ codec-weighted bitrate (Opus and AAC count for more per kbps than MP3). You then
   libraries share the better file.
 - **Ignore.** The pair is hidden from review until you un-ignore it.
 
+**Bulk review.** Switch the Review list from *Songs* to *Albums* to see one row per album (disc folders are folded in), with
+counts of upgrades, identical files, songs where the master is lower quality and approximate matches. Tick whole albums, or expand an
+album and tick individual songs, then **Link**, **Use slave copies as master**, **Ignore** or **Un-ignore** them in one go. Before
+anything runs, a preview shows how many songs will be processed and which are skipped and why, with warnings and examples for
+downgrades, approximate matches, duration mismatches and files that move folders. Downgrades are skipped unless you tick a box, and
+replacing master files needs an explicit acknowledgement. Each song then goes through the same checks as a single action.
+
 **Export.** The Review tab's **Export CSV** button downloads either the current view (filter and search applied) or the entire scan.
 Each row has the match status and type, a recommendation, both paths, where linking would place the file, codec, bitrate, sample rate,
 bit depth and duration for both sides, the quality verdict and any notes. The file opens cleanly in Excel, Numbers and LibreOffice