fix: getBlockWithTx* fetch block header and txns separately

[brbrr]

fixes #3261

[Copilot]

Pull request overview

This PR refactors block fetching to separate header and transaction retrieval as part of fixing issue #3261. The change aims to optimize performance by allowing header and transaction data to be fetched independently rather than always fetching the entire block.

Key changes:

• Added new blockTxnsByNumber helper method and TransactionsByBlockNumber blockchain reader method to fetch transactions separately
• Refactored BlockWithTxHashes and BlockWithTxs to call blockHeaderByID and blockTxnsByNumber separately instead of blockByID
• Updated blockStatus signature to accept block number directly instead of the full block

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

File	Description
rpc/v9/helpers.go	Added new blockTxnsByNumber helper to fetch transactions by block number
rpc/v9/block.go	Refactored BlockWithTxHashes and BlockWithTxs to use separate header and transaction fetches; updated blockStatus to accept block number
blockchain/blockchain.go	Added new TransactionsByBlockNumber method to Reader interface and implementation
mocks/mock_blockchain.go	Added mock implementation for TransactionsByBlockNumber method

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[codecov]

Codecov Report

❌ Patch coverage is 49.31507% with 74 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.26%. Comparing base (27e3453) to head (9bf9621).

Files with missing lines	Patch %	Lines
rpc/v10/helpers.go	23.52%	6 Missing and 7 partials ⚠️
rpc/v8/helpers.go	23.52%	6 Missing and 7 partials ⚠️
rpc/v9/helpers.go	23.52%	6 Missing and 7 partials ⚠️
rpc/v10/block.go	67.64%	3 Missing and 8 partials ⚠️
rpc/v8/block.go	62.06%	2 Missing and 9 partials ⚠️
rpc/v9/block.go	65.51%	2 Missing and 8 partials ⚠️
blockchain/blockchain.go	0.00%	3 Missing ⚠️

❌ Your patch check has failed because the patch coverage (49.31%) is below the target coverage (60.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3322      +/-   ##
==========================================
- Coverage   75.98%   75.26%   -0.73%     
==========================================
  Files         377      377              
  Lines       34614    34772     +158     
==========================================
- Hits        26301    26170     -131     
- Misses       6466     6531      +65     
- Partials     1847     2071     +224     

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