refactor(frontend): migrate state management to jotai and jotai-tanstack-query

Replace React Context + manual useEffect data fetching with jotai atoms
for state management and jotai-tanstack-query for server state caching.

- Add jotai, jotai-tanstack-query, @tanstack/query-core dependencies
- Create atoms for auth (primitive + action), feeds (suspense query),
  and articles (infinite query with cursor-based pagination)
- Wire up Provider, HydrateQueryClient, and StoreInitializer in main.tsx
- Migrate all components from useAuth() context to jotai atoms
- Replace manual fetch logic in FeedSidebar/FeedList with feedsAtom
- Replace usePaginatedArticles hook with articlesInfiniteAtom
- Add queryClient.invalidateQueries() after mutations for automatic
  cache refresh
- Add ErrorBoundary and LoadingSpinner components for Suspense support
- Remove callback prop chains (onFeedAdded, onFeedChanged, etc.)
  in favor of query invalidation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/frontend/src/components/Navigation.tsx b/frontend/src/components/Navigation.tsx
index 1f99cd6..3029e1d 100644
--- a/frontend/src/components/Navigation.tsx
+++ b/frontend/src/components/Navigation.tsx
@@ -5,12 +5,14 @@ import {
 	faRightFromBracket,
 } from "@fortawesome/free-solid-svg-icons";
 import { FontAwesomeIcon } from "@fortawesome/react-fontawesome";
+import { useAtomValue, useSetAtom } from "jotai";
 import { Link } from "wouter";
-import { useAuth } from "../contexts/AuthContext";
+import { isLoggedInAtom, logoutAtom } from "../atoms";
 import { MenuItem } from "./MenuItem";
 
 export function Navigation() {
-	const { logout, isLoggedIn } = useAuth();
+	const isLoggedIn = useAtomValue(isLoggedInAtom);
+	const logout = useSetAtom(logoutAtom);
 
 	const handleLogout = async () => {
 		await logout();