Add public curator notes and U-shaped hall wall hang.

Paintings get editable curator notes with brass plates in the 3D hall, and visit order now uses the far/end wall between left and right.

Co-authored-by: Cursor <cursoragent@cursor.com>

db/migrate-curator-notes.sql

@@ -0,0 +1,2 @@
+ALTER TABLE paintings
+  ADD COLUMN IF NOT EXISTS curator_notes TEXT NOT NULL DEFAULT '';