feat: the Paginator panel and the ColorSelector swatch round too

The Paginator's sidebar background rounds at the plate radius, and the page
area laid over its right side keeps only its outer corners so the seam with
the sidebar stays straight. Hosts that draw their own backgrounds under
extra_quads (cce-layout-interface) are unaffected: the paginator's own
backgrounds were never on that getter.

The ColorSelector's two radii (the swatch's preview radius and the selector's
own frame radius) fell back to 4px when the config left them unset, while the
field beside them carves at the TextBox radius; unset, both now follow that
radius, so the swatch and the flat frame round like the field.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

 src/layout.rs                     |  6 ++++--
 src/widget/container/paginator.rs | 22 +++++++++++++---------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/layout.rs b/src/layout.rs
index 10230e2..2d86a7e 100644
--- a/src/layout.rs
+++ b/src/layout.rs
@@ -2752,7 +2752,8 @@ pub fn set_button_font(font: &str) {
 
 pub fn color_selector_preview_corner_radius() -> f32 {
     lazy_init_style_registry();
-    get_style_registry().read().unwrap().get_float("color_selector_preview_corner_radius").unwrap_or(4.0)
+    // Unset: the swatch rounds like the text field beside it (the TextBox radius).
+    get_style_registry().read().unwrap().get_float("color_selector_preview_corner_radius").unwrap_or_else(textbox_corner_radius)
 }
 
 pub fn set_color_selector_preview_corner_radius(radius: f32) {
@@ -2764,7 +2765,8 @@ pub fn set_color_selector_preview_corner_radius(radius: f32) {
 
 pub fn color_selector_corner_radius() -> f32 {
     lazy_init_style_registry();
-    get_style_registry().read().unwrap().get_float("color_selector_corner_radius").unwrap_or(4.0)
+    // Unset: the selector's frame rounds like the text field it stands in for.
+    get_style_registry().read().unwrap().get_float("color_selector_corner_radius").unwrap_or_else(textbox_corner_radius)
 }
 
 pub fn set_color_selector_corner_radius(radius: f32) {
diff --git a/src/widget/container/paginator.rs b/src/widget/container/paginator.rs
index e7f5002..845640b 100644
--- a/src/widget/container/paginator.rs
+++ b/src/widget/container/paginator.rs
@@ -11,7 +11,7 @@
 //! - [`Paint::aggregates_child_extra_quads`] + [`Paint::forwarded_highlight`]: legacy
 //!   `extra_quads` served the strip's chrome only (cce-layout-interface renders the tab
 //!   column through that getter plus `all_rounded_quads`, which carries the strip's rounded
-//!   state fills — the paginator's own background quads live in `all_quads` alone), and
+//!   state fills — the paginator's own backgrounds live in `all_rounded_quads` alone), and
 //!   legacy `highlight_quad` forwarded to the strip's (the hovered-tab tint
 //!   cce-layout-interface draws directly).
 
@@ -176,11 +176,14 @@ impl Paint for Paginator {
 
     /// Own geometry: the sidebar background plus the page-area background — the latter is the
     /// one visual the former empty `Page` stack contributed (its bg quad over the content
-    /// area), painted directly since the pages folded away (Phase 6au).
+    /// area), painted directly since the pages folded away (Phase 6au). Both round at the
+    /// plate radius; the page area keeps only its outer corners so the seam with the sidebar
+    /// stays straight.
     fn paint(&self, rect: Rect, ctx: &mut PaintCtx) {
+        let r = crate::layout::plate_corner_radius();
         let c = self.color();
         if c[3] > 0.0 {
-            ctx.quad(rect, c);
+            ctx.rounded_rect(rect, r, (true, true, true, true), c);
         }
         if !self.page_labels.is_empty() {
             let mut pc = colors::page_color();
@@ -193,7 +196,7 @@ impl Paint for Paginator {
                     width: (rect.width - sidebar_w).max(0.0),
                     height: rect.height,
                 };
-                ctx.quad(page_rect, pc);
+                ctx.rounded_rect(page_rect, r, (false, true, true, false), pc);
             }
         }
     }
@@ -319,16 +322,17 @@ mod tests {
         ctx.register_widget(id, ptr);
 
         // Legacy split: `extra_quads` is the children's chrome only; the sidebar background
-        // quad lives in `all_quads` alone (email/layout-interface draw their own backgrounds
-        // under `extra_quads`).
+        // (a rounded rect) lives in `all_rounded_quads` alone (layout-interface draws its
+        // own backgrounds under `extra_quads`).
         let extra = WidgetHost::extra_quads(&p);
         let strip_extra = p.sidebar_menu.extra_quads();
         assert_eq!(extra.len(), strip_extra.len(), "children-only plain view (pages emit none)");
         let bg = colors::sidebar_bg_color();
         if bg[3] > 0.0 {
-            let bg_quad = (0.0, 0.0, 400.0, 300.0, bg);
-            assert!(!extra.contains(&bg_quad), "no own bg in extra_quads");
-            assert!(WidgetHost::all_quads(&p, &ctx).contains(&bg_quad), "own bg in all_quads");
+            let r = crate::layout::plate_corner_radius();
+            let bg_quad = (0.0, 0.0, 400.0, 300.0, r, bg, (true, true, true, true));
+            assert!(!extra.iter().any(|q| q.4 == bg && q.2 == 400.0), "no own bg in extra_quads");
+            assert!(WidgetHost::all_rounded_quads(&p, &ctx).contains(&bg_quad), "own bg in all_rounded_quads");
         }
 
         // The embedded strip + pages land in the registry on tick (the spatial grid feeds off