Replace Vec<u8> with Bytes

[MartinquaXD]

Description

A lot of data we have to pass around is currently stored in Vec<u8> (e.g. calldata, signatures). Cloning those is very expensive because we always need to do a full clone (fresh allocation + copying all the bytes). This can be avoided by using bytes::Bytes. That's effectively an immutable and reference counted Vec<u8> which makes clones just an atomic pointer increment.

Changes

replaced Vec<u8> with bytes::Bytes almost everywhere. Exceptions are:

• auto generated code - obviously
• database code (weirdly sqlx doesn't support that type)
• where external crate API don't allow the usage of Bytes
• solana

How to test

all tests should still pass
performance impact can be measured by temporarily deploying to prod

[MartinquaXD]

@claude do your thing

[claude]

Claude finished @MartinquaXD's task in 4m 20s —— View job

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PR Review: Replace Vec<u8> with Bytes

• Read the diff against origin/main
• Analyze changes for correctness & performance
• Post inline comments for issues found
• Post review summary

This is a clean, mechanical migration and I don't see any correctness regressions. A few things I specifically checked that hold up well:

• Wire format is preserved. Every migrated field keeps its #[serde(with = "bytes_hex")] / serde_ext::Hex adapter, so serialization stays hex-encoded and doesn't silently fall back to bytes' native byte-sequence serde impl.
• Bytes::from_static(&[...]) uses in tests all point at literal arrays / byte-strings, so const promotion to 'static is valid — no runtime data passed to from_static.
• .calldata().clone().0 pattern (alloy Bytes clone → inner bytes::Bytes) is genuinely zero-copy, nice.
• DB / solana / external-API exceptions are consistent with what the description calls out (.to_vec() only at the sqlx boundary).

One optional perf nit posted inline on crates/simulator/src/encoding.rs:111 — BytesMut::from_iter(Vec<u8>) copies element-by-element instead of memcpy; suggested extend_from_slice.

Nothing blocking from my side.
• branch use-bytes-crate