fix: resolve test failures for theme builder integration

- Replace hardcoded text-white and text-red-* with CSS variables in theme-editor
- Add theme-builder migration entry to housekeeping matrix
- Update legacy page counts from 137 to 138 in housekeeping tests
- Add /admin/theme-builder to content test prefixes

src/app/admin/theme-builder/theme-editor.tsx

@@ -239,7 +239,7 @@ export function ThemeEditor({
 									type="submit"
 									variant="outline"
 									size="sm"
-									className="text-red-500 hover:text-red-600"
+									className="text-[var(--admin-error)] hover:text-[var(--admin-error)]/80"
 									onClick={(e) => {
 										if (
 											!confirm("Delete this scope and all its theme values?")
@@ -264,7 +264,7 @@ export function ThemeEditor({
 						onClick={() => setMode("light")}
 						className={`px-3 py-1.5 text-xs font-medium transition-colors ${
 							mode === "light"
-								? "bg-[var(--admin-accent)] text-white"
+								? "bg-[var(--admin-accent)] text-[var(--admin-accent-text)]"
 								: "bg-[var(--admin-surface)] text-[var(--admin-text)] hover:bg-[var(--admin-surface-elevated)]"
 						}`}
 					>
@@ -275,7 +275,7 @@ export function ThemeEditor({
 						onClick={() => setMode("dark")}
 						className={`px-3 py-1.5 text-xs font-medium transition-colors ${
 							mode === "dark"
-								? "bg-[var(--admin-accent)] text-white"
+								? "bg-[var(--admin-accent)] text-[var(--admin-accent-text)]"
 								: "bg-[var(--admin-surface)] text-[var(--admin-text)] hover:bg-[var(--admin-surface-elevated)]"
 						}`}
 					>