feat: implement unsaved changes handling in editor and sidebar

- Introduced global state management for unsaved changes and pending navigation using Jotai atoms.
- Updated the editor component to sync local unsaved changes with global state and handle navigation prompts.
- Enhanced sidebar functionality to check for unsaved changes before navigating to a new note.
- Added cleanup logic for global state on component unmount to prevent stale data.

surfsense_web/atoms/editor/ui.atoms.ts

@@ -0,0 +1,27 @@
+import { atom } from "jotai";
+
+interface EditorUIState {
+	hasUnsavedChanges: boolean;
+	pendingNavigation: string | null; // URL to navigate to after user confirms
+}
+
+export const editorUIAtom = atom<EditorUIState>({
+	hasUnsavedChanges: false,
+	pendingNavigation: null,
+});
+
+// Derived atom for just the unsaved changes state
+export const hasUnsavedEditorChangesAtom = atom(
+	(get) => get(editorUIAtom).hasUnsavedChanges,
+	(get, set, value: boolean) => {
+		set(editorUIAtom, { ...get(editorUIAtom), hasUnsavedChanges: value });
+	}
+);
+
+// Derived atom for pending navigation
+export const pendingEditorNavigationAtom = atom(
+	(get) => get(editorUIAtom).pendingNavigation,
+	(get, set, value: string | null) => {
+		set(editorUIAtom, { ...get(editorUIAtom), pendingNavigation: value });
+	}
+);