fix(frontend): land SSE notification updates in the cache keys readers use

[Oyintarede]

Closes #1071

Summary

The live notifications SSE stream (useNotificationStream) pushed incoming notifications into the TanStack Query cache with queryClient.setQueryData(queryKeys.notifications.all()), which targets the exact key ["notifications"]. But nothing reads that key:

• the bell dropdown reads useNotifications() → ["notifications", {}]
• the inbox page reads useNotifications({ limit, type, unread }) → ["notifications", { limit, type, unread }]

Because setQueryData only matches an exact key (unlike invalidateQueries, which matches by prefix), the write landed in a cache entry no component subscribes to. Live notifications therefore only appeared after the 60s refetchInterval poll — defeating the whole purpose of the SSE push.

What changed

• useNotificationStream.ts: switched from setQueryData to queryClient.setQueriesData({ queryKey: queryKeys.notifications.all() }, updater). setQueriesData with a prefix queryKey filter writes to every cache entry whose key starts with ["notifications"], so both the dropdown and inbox keys receive the update immediately. The init-merge and unread-count logic is unchanged.
• useNotificationStream.test.tsx (new): regression test asserting that (1) a streamed notification appears in the list reader's cache entry without waiting for the 60s poll, and (2) init merges and unread-count recomputation still work on the list key.

Incidental fixes (pre-existing)

While verifying the change, two unrelated issues blocked a green typecheck/lint on this branch and are included so CI passes:

• useRepaymentOperation.ts: useRepaymentOperation referenced queryClient without a useQueryClient() binding — added it.
• WalletProvider.tsx: a Prettier formatting nit.

Verified

• Stream updates land in the same cache entry the dropdown and inbox read
• A pushed notification shows up in the bell/inbox without waiting for the 60s poll
• Init-merge and unread-count still work after the key change
• New test asserts a streamed notification updates the rendered list
• npm test (234 tests pass), npm run lint, and npm run typecheck green

Out of scope (per issue): backend SSE behavior and action_url deep-linking.