feat: address UTxOs and transactions REST endpoints

[whankinsiv]

Description

• Adds handlers /addresses/{address}/utxos and /addresses/{address}/transactions in rest_blockfrost.
• Introduces GetTransactionHashesAndTimestamps to avoid multiple chain_store queries for timestamps and transaction hashes.
• Refactors GetUTxOHashes to return QueryError instead of silently failing when UTxO hashes cannot be retrieved.
• Refactors get_utxos and get_address_utxos to return an empty Vec instead of None if an address has ever had UTxOs stored, matching Blockfrost behavior.
• Adds clear-on-start config option to address_state with default true.

Related Issue(s)

#335

How was this tested?

• Compared REST output against Blockfrost for Byron and Shelley addresses across both endpoints.

Checklist

• My code builds and passes local tests
• I added/updated tests for my changes, where applicable
• I updated documentation (if applicable)
• CI is green for this PR

Impact / Side effects

None

Reviewer notes / Areas to focus

• Query handlers in chain_store.rs

[lowhung]

Great work will 👍