minor run loop refactoring

[zander-xyz]

No description provided.

[Copilot]

Pull Request Overview

This PR refactors the block processing logic to improve the ordering of operations and optimize cache entry management. The key change moves block cache insertion earlier in the execution flow, allowing senders and authorities to be populated directly into the cached entry rather than using a temporary set.

• Moved block cache insertion before sender/authority collection in runloop_monad.cpp
• Refactored process_ethereum_block to return the output header instead of computing the block hash internally
• Added compile-time size and alignment assertions for MonadChainContext

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
cmd/monad/runloop_monad.cpp	Reordered block cache insertion and validation; eliminated temporary senders_and_authorities set
cmd/monad/runloop_ethereum.cpp	Changed return type to BlockHeader; moved block hash computation to caller
category/execution/monad/chain/monad_chain.hpp	Added static assertions for MonadChainContext size and alignment

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[kjcamann]

This looks a lot cleaner