feat: registration, delegation, and MIR history account endpoints

[whankinsiv]

This PR implements 3 of the 10 remaining account related endpoints described in #256:

• /accounts/{stake_address}/registrations - Queries historical_accounts_state for registration history, then fetches TxHash values from chain_store using each TxIdentifier to construct the Blockfrost aligned response.
• /accounts/{stake_address}/delegations - Queries historical_accounts_state for delegation history, resolving TxHash via chain_store.
• /accounts/{stake_address}/mirs - Queries historical_accounts_state for MIR history, resolving TxHash via chain_store.

Main changes:

• Registered 3 endpoints in rest_blockfrost initialization.
• Added and implemented handle_account_registrations_blockfrost, handle_account_delegations_blockfrost, and handle_account_mirs_blockfrost to handlers/accounts.rs.

Notes:

• The registrations endpoint currently returns 0 for the amount field as this data isn't included in the certificate message. I am still considering the best approach for handling this and am currently leaning towards moving the historical epoch stakes data from accounts_state to historical_accounts_state although this would require passing the per stake address distribution on the message bus. Alternatively, we could rely on a second query in the rest handler to retrieve the account epoch stake from accounts_state under the assumption that spdd-retention-epochs is configured to store all epochs.

Next steps:

• The next PR for Implement BlockFrost /accounts endpoints #256 will add withdrawal processing to historical_accounts_state and implement the corresponding REST handler.

[whankinsiv]

Awaiting the review/merge of #272 before moving to ready for review.