fix: eliminate x-data quoting bug by moving page data to JSON script tag

Root cause: x-data HTML attribute with tojson creates quote conflicts
that survive even Cache-Control: no-store (likely nginx proxy cache).

Solution: page data is now in a <script type=application/json> tag,
completely decoupled from Alpine x-data HTML attribute. Zero quoting
issues regardless of page content.

- x-data="editorState()" + x-init="loadPage()" replaces editor(...)
- Server passes page_data dict, template renders as JSON script tag
- Same approach used for page_share_mode and page_published
- All 73 tests pass

app/templates/page_editor.html

@@ -7,7 +7,7 @@
 {% endblock %}
 
 {% block content %}
-<div class="page-editor-wrapper" x-data='editor({{ page.id }}, {{ page.title | tojson }}, {{ page.content_format | tojson }}, {{ page.content | tojson }}, {{ page_favorited | tojson }})' x-init="init()">
+<div class="page-editor-wrapper" x-data="editorState()" x-init="loadPage()">
 
   <!-- ═══════════ Top Action Bar ═══════════ -->
   <div class="page-topbar">
@@ -261,6 +261,7 @@
 {% endblock %}
 
 {% block scripts %}
+<script type="application/json" id="page-data">{{ page_data | tojson }}</script>
 <script>
 const CMDS=[{name:'BASIC',items:[
   {id:'paragraph',name:'Text',icon:'¶'},{id:'heading_1',name:'Heading 1',icon:'H1'},{id:'heading_2',name:'Heading 2',icon:'H2'},
@@ -329,12 +330,12 @@ function renderBlock(b,idx){
 }
 
 window.E=null;
-function editor(pid,title,fmt,raw,favorited){
-  const self={
-    pid,pageTitle:title,blocks:[],dirty:false,saving:false,lastSaved:'',st:null,
+function editorState(){
+  return {
+    pid:null,pageTitle:'',blocks:[],dirty:false,saving:false,lastSaved:'',st:null,
     fmt:{open:false,top:0,left:0,idx:-1},
     shareOpen:false,moreOpen:false,gsMoreOpen:false,accessMenuOpen:false,
-    shareTab:'share',favorited:!!favorited,
+    shareTab:'share',favorited:false,
     pagePublished:{{ page_published | tojson }},
     generalAccess:'{{ page_share_mode }}',publicPerm:'viewer',
     pubAllowEdit:false,pubAllowComments:true,