refactor(atoms): migrate to jotai-tanstack-query from custom reloadable atoms

Replace custom createReloadableAtom/createReloadableAtomFamily with
atomWithSuspenseQuery from jotai-tanstack-query, leveraging TanStack
Query's built-in caching, invalidation, and Suspense support.

- Add @tanstack/query-core and jotai-tanstack-query dependencies
- Create shared QueryClient instance (src/client/queryClient.ts)
- Migrate all data atoms (decks, cards, study, noteTypes) to atomWithSuspenseQuery
- Update page components to use .data destructuring and queryClient.invalidateQueries()
- Update all test files to use QueryClient for data hydration
- Remove src/client/atoms/utils.ts (no longer needed)

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

1 files changed, 0 insertions, 3 deletions

diff --git a/src/client/atoms/index.ts b/src/client/atoms/index.ts
index 1e13222..1de2544 100644
--- a/src/client/atoms/index.ts
+++ b/src/client/atoms/index.ts
@@ -37,6 +37,3 @@ export {
 	syncStatusAtom,
 	useSyncInit,
 } from "./sync";
-
-// Utilities
-export { createReloadableAtom, createReloadableAtomFamily } from "./utils";