fix: 500 error on /pages/{id} — missing page_share_mode in dashboard.py

dashboard.router is registered before board.router in main.py, so its
/pages/{page_id} takes priority. It was missing page_share_mode and
page_published template variables, causing Jinja2 TypeError.

app/routers/dashboard.py

@@ -166,7 +166,10 @@ async def view_page_root(request: Request, page_id: int):
             "SELECT id, title FROM pages WHERE parent_id=? ORDER BY updated_at DESC",
             (page_id,),
         ).fetchall()
-    ctx = {**sidebar, "page": page, "sub_pages": [dict(s) for s in subs], "page_favorited": False}
+    ctx = {**sidebar, "page": page, "sub_pages": [dict(s) for s in subs],
+           "page_favorited": False,
+           "page_share_mode": page.get("share_mode", "private"),
+           "page_published": bool(page.get("published", 0))}
     template = env.get_template("page_editor.html")
     return template.render(**ctx)