fix: page mode toggle no longer overwrites default preference (#1996)

The header edit/read toggle now controls only the current session's mode
without saving it as the user's preference. The saved preference (set in
profile settings) is applied once on initial load and sticks across page
navigations within the session, so navigating to a new page no longer
resets the mode mid-session.

Fixes #1693

apps/client/src/features/editor/atoms/editor-atoms.ts

@@ -1,5 +1,6 @@
 import { atom } from "jotai";
 import { Editor } from "@tiptap/core";
+import { PageEditMode } from "@/features/user/types/user.types.ts";
 
 export const pageEditorAtom = atom<Editor | null>(null);
 
@@ -12,3 +13,7 @@ export const yjsConnectionStatusAtom = atom<string>("");
 export const showAiMenuAtom = atom(false);
 
 export const showLinkMenuAtom = atom(false);
+
+// Current page's edit mode — initialized from the user's saved preference on
+// first load, can be toggled locally without persisting to the server.
+export const currentPageEditModeAtom = atom<PageEditMode>(PageEditMode.Edit);