[SDK · Network & Horizon] Implement HorizonClient wrapper — transactions endpoint

[amina69]

Epic: Network & Horizon
Labels: network, tx, sdk
Size: S (~1 day)

Description

Wrap the Horizon transactions endpoint for fetching transaction history and individual transactions.

Tasks

• getTransaction(hash): fetch single transaction by hash
• getAccountTransactions(accountId, {limit, cursor}): paginated transaction list
• On 404: return null (not an error for polling)
• Support cursor-based pagination, return nextCursor
• Unit test: fetch by hash, not found returns null, pagination