world books open, and anvils stop offering a cursor gear

- clicking a book in the world opens it and turns its pages: letters and world books share one reader
- the cursor's object rules are the client's own 31-row strategy table now, so decorative objects stop pretending to be usable
- trainer and tradeskill windows draw each row's icon by the reference's own law, and the trainer's filter dropdown toggles again
- water color follows the zone's light blend, so lakes stop snapping between area tints

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

crates/benilla-ui/src/script/extract.rs

@@ -209,9 +209,19 @@ impl UiScript {
                             alpha_gradient: data.alpha_gradient,
                         }
                     } else {
+                        // The draw gate is the TEXTURE slot, never the colour (`0x7706e0`: `+0xcc`
+                        // empty -> emit NOTHING — `texture-color-composition.md` §4, VERIFIED). A
+                        // vertex colour is a tint on whatever texture exists; alone it is not
+                        // drawable content — it survives `SetTexture(nil)` by design ("a tint
+                        // outlives the art it was tinting") and used to leak out of here as a
+                        // solid plate the moment the art was cleared (the white action buttons on
+                        // a character switch; the 2026-07-10 grey wells were the same class).
+                        let has_texture = data.texture.is_some() || data.fill.is_some();
                         QuadContent::Texture {
                             path: data.texture,
-                            color: texture_color(data.fill, data.vertex_color),
+                            color: has_texture
+                                .then(|| texture_color(data.fill, data.vertex_color))
+                                .flatten(),
                             additive: data.additive,
                             tex_coords: data.tex_coords,
                             circular: data.circular,