Add Container component and fix radius/maxWidth theming

- Drop buttonRadius prop; button now uses --radius via rounded-md
- Inject @theme radius mappings into ThemeProvider so rounded-* utilities
  pick up --radius inside the Tailwind CDN iframe
- Add shared Container that consumes --container-max-width set from the
  global maxWidth prop, replacing ad-hoc "container mx-auto max-w-7xl px-6"
  wrappers across commerce, landing, footer, navigation, and others
- Simplify maxWidth options to Small/Medium/Large/X-Large/Full bleed and
  shift the scale up so Large (1280px) matches the previous default

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

config/root.tsx

@@ -32,9 +32,8 @@ export const Root: RootConfig<{
     fgColor: "#0a0a0a",
     mutedColor: "#f5f5f5",
     radius: "md",
-    buttonRadius: "md",
     shadow: "sm",
-    maxWidth: "xl",
+    maxWidth: "lg",
   },
   fields: {
     title: { label: "Page title", type: "text" },
@@ -59,17 +58,6 @@ export const Root: RootConfig<{
         { label: "Extra large", value: "xl" },
       ],
     },
-    buttonRadius: {
-      label: "Button radius",
-      type: "select",
-      options: [
-        { label: "None (square)", value: "none" },
-        { label: "Small", value: "sm" },
-        { label: "Medium", value: "md" },
-        { label: "Large", value: "lg" },
-        { label: "Extra large", value: "xl" },
-      ],
-    },
     shadow: {
       label: "Shadow",
       type: "select",
@@ -89,7 +77,6 @@ export const Root: RootConfig<{
         { label: "Medium", value: "md" },
         { label: "Large", value: "lg" },
         { label: "Extra large", value: "xl" },
-        { label: "2X large", value: "2xl" },
         { label: "Full bleed", value: "full" },
       ],
     },
@@ -105,8 +92,8 @@ export const Root: RootConfig<{
     fgColor,
     mutedColor,
     radius,
-    buttonRadius,
     shadow,
+    maxWidth,
   }) => {
     return (
       <ThemeProvider
@@ -119,8 +106,8 @@ export const Root: RootConfig<{
         fgColor={fgColor}
         mutedColor={mutedColor}
         radius={radius}
-        buttonRadius={buttonRadius}
         shadow={shadow}
+        maxWidth={maxWidth}
       >
         {children}
       </ThemeProvider>