Smooth the page's text in the foundation, not per surface

The showcase and the error pages set grayscale font smoothing on
themselves, but the foundation did not, so an application that dropped
Tailwind's antialiased class rendered heavier text on macOS than the
package's own pages, silently. base.css now sets it on the page; the
showcase's and error page's copies go, and the guard tells a leftover
antialiased class to go too. Decided with the user (plan step 46).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

resources/css/foundation/base.css

@@ -8,6 +8,11 @@
  * `--md-ref-typeface-brand` (tokens/type.css), Google Sans Flex from tokens/font.css, whose
  * `@font-face` this file imports into the same layer.
  *
+ * Text is smoothed in grayscale where a platform offers the choice (macOS browsers): Google Sans
+ * Flex is drawn for it, and subpixel smoothing thickens its strokes on light text over a dark
+ * surface. Every surface the package draws — the showcase, the error pages — is set this way,
+ * and so is an application, which drops Tailwind's `antialiased` class with nothing to replace.
+ *
  * In `material.base`, above the reset and below every component and text class.
  */
 
@@ -20,5 +25,7 @@
         background-color: var(--md-sys-color-surface);
         color: var(--md-sys-color-on-surface);
         font-family: var(--md-ref-typeface-brand);
+        -webkit-font-smoothing: antialiased;
+        -moz-osx-font-smoothing: grayscale;
     }
 }