Fix stale @starknet-react/core imports and cairo test arity mismatch

[tu11aa]

Summary

• app/page.tsx:8 imported useBlockNumber from @starknet-react/core, the old package name (identical fix and byte-identical line to PR Fix stale @starknet-react/core import and cairo test arity mismatch #21 on step-2, verified character-for-character).
• app/vesu/page.tsx:11 imported useAccount from the same old package. Repointed to ~~/hooks/useAccount — the local wrapper every other standalone useAccount consumer in the codebase uses (ConnectedAddress.tsx, WriteOnlyFunctionForm.tsx, FaucetButton.tsx, useAutoConnect.ts, useTargetNetwork.ts, CustomConnectButton/index.tsx). This file only destructures .address, matching that convention (the two exceptions using the raw package, Header.tsx and NetworkOptions.tsx, do so because they import multiple hooks — useNetwork/useProvider/useSwitchChain — in one line).
• contracts/tests/test_contract.cairo:110 — same arity fix as step-2 (byte-identical content, verified via diff).

No refactors, no unrelated cleanup. deployedContracts.ts untouched (D1, out of scope).

Proof (pasted command output)

Compile: ⏭️ Skipping compilation - all contracts are up to date

Test:

Collected 5 test(s) from contracts package
Running 5 test(s) from tests/
[PASS] contracts_integrationtest::test_contract::test_withdraw_not_owner
[PASS] contracts_integrationtest::test_contract::test_set_greetings
[PASS] contracts_integrationtest::test_contract::test_set_greeting_no_allowance
[PASS] contracts_integrationtest::test_contract::test_transfer_eth
[PASS] contracts_integrationtest::test_contract::test_transfer_strk
Running 0 test(s) from src/
Tests: 5 passed, 0 failed, 0 ignored, 0 filtered out

Compile-clean (E2030 gone) and full pass, including the 3 #[fork("SEPOLIA_LATEST")] tests.

yarn format:check / scarb fmt --check: both clean, exit 0 — no reformatting needed.

next:check-types / yarn build: fail, both pre- and post-deploy, but due to a separate, pre-existing defect unrelated to this fix — a symbol-typed index-signature error in ContractUI.tsx/DebugContracts.tsx/useDeployedContractInfo.ts/contract.ts:56, traced to a contract-name union mismatch (likely vStrk/mainnetFork missing from predeployedContracts.ts relative to scaffold.config.ts's targetNetworks: [chains.mainnetFork]). Verified via git stash that this failure is present identically with or without this PR's changes — it is not a regression from this fix and is out of this PR's scope (D2/D3 only).

next dev (port 3002):

curl / -> HTTP_STATUS:200
curl /vesu -> HTTP_STATUS:200

Both routes render — the actual proof the frontend works, independent of the strict-build type error above.

Test plan

• yarn compile
• yarn test (5/5 pass)
• yarn format:check (clean)
• next dev on port 3002, curl / → 200, curl /vesu → 200
• yarn next:check-types / yarn build — fails on a pre-existing, unrelated defect (see above), not introduced or fixed by this PR