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/schema.sql

@@ -60,6 +60,7 @@ CREATE TABLE IF NOT EXISTS paintings (
     year INTEGER,
     year_end INTEGER,
     description TEXT,
+    curator_notes TEXT NOT NULL DEFAULT '',
     image_path VARCHAR(500),
     thumbnail_path VARCHAR(500),
     wikipedia_title VARCHAR(300),