Add debug logging to page registry pipeline

Server-side: log page count, output size, and first 200 chars in _build_pages_sx.
Client-side: log script tag count, text length, parsed entry count in processPageScripts.
Helps diagnose why pages: 0 routes loaded.

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

shared/sx/helpers.py

@@ -646,11 +646,15 @@ def _build_pages_sx(service: str) -> str:
     ``parse`` function.  Each dict has keys: name, path, auth, has-data,
     content, closure.
     """
+    import logging
+    _log = logging.getLogger("sx.pages")
     from .pages import get_all_pages
     from .parser import serialize as sx_serialize
 
     pages = get_all_pages(service)
+    _log.debug("_build_pages_sx(%s): %d pages in registry", service, len(pages))
     if not pages:
+        _log.warning("_build_pages_sx(%s): no pages found — page registry will be empty", service)
         return ""
 
     entries = []
@@ -679,7 +683,9 @@ def _build_pages_sx(service: str) -> str:
         )
         entries.append(entry)
 
-    return "\n".join(entries)
+    result = "\n".join(entries)
+    _log.debug("_build_pages_sx(%s): built %d entries, %d bytes", service, len(entries), len(result))
+    return result
 
 
 def _sx_literal(v: object) -> str:
@@ -752,8 +758,13 @@ def sx_page(ctx: dict, page_sx: str, *,
         styles_json = _build_style_dict_json()
 
     # Page registry for client-side routing
+    import logging
+    _plog = logging.getLogger("sx.pages")
     from quart import current_app
     pages_sx = _build_pages_sx(current_app.name)
+    _plog.debug("sx_page: pages_sx %d bytes for service %s", len(pages_sx), current_app.name)
+    if pages_sx:
+        _plog.debug("sx_page: pages_sx first 200 chars: %s", pages_sx[:200])
 
     return _SX_PAGE_TEMPLATE.format(
         title=_html_escape(title),