Use ASW --width-lg token for garden width instead of hardcoded selector

ASW now has body > main container rule (fixed upstream c6247ae).
Garden overrides --width-lg: 800px instead of fighting specificity.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/css/garden.css

@@ -58,9 +58,10 @@ body {
   font-family: var(--garden-font);
 }
 
-/* ── Layout — contained, not a billboard ───────────────────── */
-body > main, body > nav, body > footer {
-  max-width: 800px;
+/* ── Layout — ASW handles body > main container now ────────── */
+/* Override --width-lg for narrower garden feel */
+:root {
+  --width-lg: 800px;
 }
 
 /* ── Links — violet accent, indigo hover ──────────────────── */