Describe shift-click range selection in the hierarchy (#241)

- Scene editing: shift-click selects all rows between the anchor and
  the clicked row. Ctrl+shift adds the range.
- Development: check total is now 1443.

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

Development.md

@@ -15,7 +15,7 @@ npm run build        # writes dist/ and regenerates index.html
 php tools/make-user.php <name> <password> [admin|user]        # an account; every tool signs in (see Accounts)
 php tests/php/accounts.test.php                               # the API's account rules, no server needed (CI's gate job)
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1442 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1443 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result

Scene-editing.md

@@ -163,6 +163,11 @@ group. There are no groups inside groups.
 - **A plain click on a row that is already selected** along with others keeps only that row
   selected, a member of a group included. The press alone changes nothing yet, the release does, so
   a drag that starts there leaves the selection as it was.
+- **Shift-click selects a range:** every row from the last plain or Ctrl-click to the clicked one,
+  upwards or downwards. A folded group in the range brings all its members; children folded away
+  under a parent stay out. A second Shift-click redraws the range from the same row, Ctrl+Shift adds
+  the range to the selection. Without a selected row to start from, Shift-click adds the one row as
+  before.
 - **Dragging** an object onto the group row puts it in behind the last member; dropping it into
   the gap between two members puts it there, dropping it beside a row outside the group takes it
   out. The group row itself drags as one block between top-level rows.