fix(front): clean localStorage on user change

- fix issue with selected drive and user logout/login via another user
    (was raising a "404 not found")
    - normalize all localStorage to "oxi-" prefix
    - add a specific frontend/AGENTS.md for frontend part (stop increasing the global AGENTS.md)

frontend/src/routes/login/+page.svelte

@@ -107,7 +107,7 @@
 				);
 				return;
 			}
-			session.user = data.user;
+			session.setUser(data.user);
 			await goto(resolve(redirectTarget), { replaceState: true });
 		} catch (err) {
 			error = err instanceof Error ? err.message : t('auth.login_error', 'Error logging in');
@@ -203,7 +203,7 @@
 		if (oidcCode) {
 			const user = await exchangeOidcCode(oidcCode);
 			if (user) {
-				session.user = user;
+				session.setUser(user);
 				await goto(resolve(redirectTarget), { replaceState: true });
 				return;
 			}
@@ -214,7 +214,7 @@
 		try {
 			const me = await fetchMe();
 			if (me) {
-				session.user = me;
+				session.setUser(me);
 				await goto(resolve(redirectTarget), { replaceState: true });
 				return;
 			}

frontend/src/routes/login/page.test.ts

@@ -1,11 +1,22 @@
 import { it, expect, vi, beforeEach } from 'vitest';
 import { render, screen, fireEvent, waitFor } from '@testing-library/svelte';
 
-const { goto, pageState, session } = vi.hoisted(() => ({
-	goto: vi.fn(),
-	pageState: { url: new URL('http://localhost/login') } as { url: URL },
-	session: { user: null } as { user: unknown }
-}));
+const { goto, pageState, session } = vi.hoisted(() => {
+	// `setUser` mirrors the real SessionStore method: sets the user and
+	// runs `ensureActiveUser` (localStorage cleanup on account switch).
+	// Tests don't care about the cleanup; the mock just assigns.
+	const store: { user: unknown; setUser: (u: unknown) => void } = {
+		user: null,
+		setUser(u) {
+			store.user = u;
+		}
+	};
+	return {
+		goto: vi.fn(),
+		pageState: { url: new URL('http://localhost/login') } as { url: URL },
+		session: store
+	};
+});
 vi.mock('$app/navigation', () => ({ goto }));
 vi.mock('$app/state', () => ({ page: pageState }));
 vi.mock('$lib/stores/session.svelte', () => ({ session }));

frontend/src/routes/photos/+page.svelte

@@ -37,8 +37,8 @@
 
 	type GroupMode = 'day' | 'month' | 'year';
 	type LayoutMode = 'square' | 'justified';
-	const GROUP_KEY = 'oxicloud-photos-group';
-	const LAYOUT_KEY = 'oxicloud-photos-layout';
+	const GROUP_KEY = 'oxi-photos-group';
+	const LAYOUT_KEY = 'oxi-photos-layout';
 	let groupMode = $state<GroupMode>('month');
 	let layoutMode = $state<LayoutMode>('square');
 	const selected = useSelection();

frontend/src/routes/s/[token]/+page.svelte

@@ -18,7 +18,7 @@
 	type Crumb = { id?: string; name: string };
 	type ViewMode = 'grid' | 'list';
 
-	const VIEW_KEY = 'oxicloud_share_view';
+	const VIEW_KEY = 'oxi-share-view';
 	const token = $derived(page.params.token ?? '');
 
 	let view = $state<State>('loading');