feat(history): enable transaction history on Base

Plug in the deployed pearl-transactions subgraph URL for Base
(https://transactions-base.subgraph.autonolas.tech/), replacing the
undefined placeholder that surfaced the 'not available on this network
yet' state.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: atepem

frontend/constants/urls.ts

@@ -41,7 +41,7 @@ export const TRANSACTION_HISTORY_SUBGRAPH_URLS_BY_EVM_CHAIN: Partial<
   [EvmChainIdMap.Polygon]: undefined,
   [EvmChainIdMap.Optimism]:
     'https://transactions-optimism.subgraph.autonolas.tech/',
-  [EvmChainIdMap.Base]: undefined,
+  [EvmChainIdMap.Base]: 'https://transactions-base.subgraph.autonolas.tech/',
 };
 
 // telegram