Fix page registry: process page scripts before mount scripts

The data-mount="body" script replaces the entire body content,
destroying the <script type="text/sx-pages"> tag. Moving
processPageScripts before processSxScripts ensures the page
registry is read before the body is replaced.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/ref/boot.sx

@@ -344,8 +344,8 @@
       (log-info (str "sx-browser " SX_VERSION))
       (init-css-tracking)
       (init-style-dict)
-      (process-sx-scripts nil)
       (process-page-scripts)
+      (process-sx-scripts nil)
       (sx-hydrate-elements nil)
       (process-elements nil))))