Move the stats site into a stats/ subdir to keep the album root small

The filter mini-albums put thousands of HTML files directly in the album root.
Reorganise so only the main album lives in DIST_DIR and all stats content goes
under stats/:

  stats/index.html              - the stats overview (was stats.html)
  stats/<pagebase>/index.html   - each filter gallery (was <pagebase>.html)
  stats/<pagebase>/<index>.html - each filter view page (was <pagebase>--N.html)

Each mini-album is its own directory, so no single directory holds more than one
filter's pages. Links updated accordingly: the overview links to <pagebase>/, the
gallery thumbnails link to sibling <index>.html, view prev/next/gallery are
same-dir, and assets/album-details/back-to-stats resolve via the ../.. backhref.
The header Stats link and camera.tmpl back link point at stats/index.html.

Mini-albums still reuse the shared photos/thumbs/blurs assets and render in
parallel. Tests and the dry-run plan updated for the new layout; README documents
the stats/ subdirectory structure.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 14 insertions, 4 deletions

diff --git a/README.md b/README.md
index 6095e57..219d051 100644
--- a/README.md
+++ b/README.md
@@ -163,11 +163,21 @@ By default, the generated root `index.html` is a no-JavaScript splash page using
 a randomly selected album photo. Set `SPLASH_PAGE=no` or pass `--no-splash` to
 restore the top-level redirect to `page-1.html`.
 
-By default, `shuriken` also generates `stats.html`, a no-JavaScript page with
+By default, `shuriken` also generates a no-JavaScript stats site with
 EXIF-derived insights (camera leaderboard, shooting dates, exposure, dimension,
-and format breakdowns) plus one `camera-<slug>.html` per camera linked from the
-leaderboard, and shows a `Stats` link in the page header bar. Set `STATS_PAGE=no`
-or pass `--no-stats` to skip the stats and per-camera pages and hide the link.
+format, and decoded-enum breakdowns), reachable from the `Stats` link in the page
+header bar. Every row on the stats overview is clickable: each bucket (each
+camera, ISO, year, aperture, orientation, …) is its own filter "mini-album" — a
+gallery of just the matching photos with view pages whose previous/next cycle
+within that filter.
+
+To keep the album root uncluttered, all of this lives under a `stats/`
+subdirectory: the overview is `stats/index.html` and each mini-album is its own
+directory `stats/<filter>/` (gallery `index.html` plus numbered view pages). Only
+the main album sits in `DIST_DIR` itself. The mini-album pages reuse the album's
+shared `photos/`, `thumbs/`, and `blurs/` assets (only the HTML is per-filter)
+and are rendered in parallel honouring `IMAGE_JOBS`. Set `STATS_PAGE=no` or pass
+`--no-stats` to skip the whole `stats/` tree and hide the link.
 
 To quickly pick a new random splash photo for an already generated album, run
 `shuriken --refresh-splash`. This rewrites only `DIST_DIR/index.html` using