refactor(client): migrate state management from React Context to Jotai

Replace AuthProvider and SyncProvider with Jotai atoms for more granular
state management and better performance. This migration:

- Creates atoms for auth, sync, decks, cards, noteTypes, and study state
- Uses atomFamily for parameterized state (e.g., cards by deckId)
- Introduces StoreInitializer component for subscription initialization
- Updates all components and pages to use useAtomValue/useSetAtom
- Updates all tests to use Jotai Provider with createStore pattern

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/client/atoms/cards.ts b/src/client/atoms/cards.ts
new file mode 100644
index 0000000..f053ab9
--- /dev/null
+++ b/src/client/atoms/cards.ts
@@ -0,0 +1,31 @@
+import { apiClient } from "../api/client";
+import { createReloadableAtomFamily } from "./utils";
+
+export interface Card {
+	id: string;
+	deckId: string;
+	noteId: string;
+	isReversed: boolean;
+	front: string;
+	back: string;
+	state: number;
+	due: string;
+	reps: number;
+	lapses: number;
+	createdAt: string;
+	updatedAt: string;
+}
+
+// =====================
+// Cards by Deck - Suspense-compatible
+// =====================
+
+export const cardsByDeckAtomFamily = createReloadableAtomFamily(
+	async (deckId: string) => {
+		const res = await apiClient.rpc.api.decks[":deckId"].cards.$get({
+			param: { deckId },
+		});
+		const data = await apiClient.handleResponse<{ cards: Card[] }>(res);
+		return data.cards;
+	},
+);