Add external_hash to bundle

[dvush]

📝 Summary

• raw bundle has new optional bundle_hash field that is set by the sender to uniquely identify bundle
• bundle has this new hash in the external_hash field

💡 Motivation and Context

This allows ingress service to set bundle hash that is returned to the user.

✅ I have completed the following steps:

• Run make lint
• Run make test
• Added tests (if applicable)

[Copilot]

Pull Request Overview

Adds support for an externally provided unique identifier for bundles.

• Introduces external_hash: Option on Bundle and bundle_hash: Option on RawBundleMetadata.
• Wires encode/decode so RawBundleMetadata.bundle_hash maps to Bundle.external_hash.
• Updates logic to prefer the external hash where appropriate (redistribution and blocks processor) and adjusts tests/test helpers.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
crates/rbuilder-primitives/src/lib.rs	Adds external_hash field to Bundle with documentation.
crates/rbuilder-primitives/src/serialize.rs	Adds bundle_hash to RawBundleMetadata and maps to/from Bundle.external_hash.
crates/rbuilder-primitives/src/order_builder.rs	Initializes external_hash: None in BundleBuilder.
crates/rbuilder-primitives/src/test_data_generator.rs	Initializes external_hash: None in test data helpers.
crates/rbuilder/src/backtest/redistribute/mod.rs	Uses external_hash.unwrap_or(hash) when tracking bundle hashes.
crates/rbuilder-operator/src/blocks_processor.rs	Prefers external_hash over hash when reporting bundle_hash; updates test metadata.
crates/rbuilder/src/backtest/build_block/synthetic_orders.rs	Initializes external_hash: None in synthetic bundle creation.
crates/rbuilder/src/backtest/restore_landed_orders/find_landed_orders.rs	Updates tests to set external_hash: None.
crates/rbuilder/src/building/builders/parallel_builder/conflict_resolvers.rs	Updates tests to set external_hash: None.
crates/rbuilder/src/backtest/store.rs	Populates bundle_hash: None in RawBundleMetadata in tests.

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[Copilot]

Pull Request Overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 3 comments.

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