fix: Prevent root level page from overwriting home page ID

Critical bug: When processing root-level pages (sectionName === null),
the first page's ID was overwriting the home page ID in syncedPages map.
This caused all subsequent sections to use the wrong parent.

Example bug:
  - First root page 'Solution Draft' (id=101) overwrote home (id=100)
  - 'Subscriptions' section then used 101 as parent instead of 100
  - Result: Subscriptions appeared under Solution Draft instead of Home

Fix: Only update syncedPages map for actual sections (sectionName !== null),
never for root level which should always remain the home page ID.

All tests passing (148/148).

Author: agpenton

dist/index.js

@@ -171,7 +171,8 @@ async function syncPages(home, localPages, sectionHierarchy, renderer) {
 
             // The first page in this section represents the section
             // Store its ID so child sections can reference it
-            if (i === 0 && syncedPage && syncedPage.id) {
+            // Don't overwrite the root level (null) which is set to home page ID
+            if (i === 0 && sectionName !== null && syncedPage && syncedPage.id) {
                 syncedPages.set(sectionName, syncedPage.id);
             }
         }