Add deterministic order book delta validation

[Soengkit]

Summary

Adds deterministic order book snapshot and delta validation coverage for #4, including state-preservation checks for malformed, stale, out-of-order, and checksum-mismatched payloads.

Changes

• Added DepthDelta, DepthDeltaLevel, ApplySnapshot, and ApplyDelta helpers for local order book delta handling.
• Added deterministic checksum support for post-delta book validation.
• Added tests covering valid snapshot + delta application, malformed symbol/side/price/quantity payloads, stale and out-of-order sequence rejection, and checksum mismatch rejection without mutating the current book.
• Included diagnostic/build-182f71ab.json and diagnostic/build-182f71ab.logd from the required build run.

Testing

• cd market && go test ./orderbook ./matching ./ws - pass
• python3 build.py - 8/10 modules pass; market passes. Existing unrelated local failures remain in frailbox on macOS (MAP_HUGETLB) and openapi-haskell due missing Haskell packages (Data.Yaml / related modules). Diagnostic artifacts were generated successfully.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

---

• I would like to request that my diagnostic build log is removed before merging

Closes #4

[Peter7896]

Thanks for the PR. This is the current candidate for the WebSocket/order book delta validation bounty.

Before this can be forwarded for upstream bounty review, I need to verify the diagnostic bundle and scope. Please keep the PR focused on issue #4, make sure the diagnostic files are exactly what python3 build.py generated on this branch, and avoid manual edits to generated diagnostic output.

If this PR remains fork-only, an upstream PR against lobster-trap/Kickama will still be needed for merge and payout review.

[Soengkit]

Thanks for the clarification. I opened the upstream PR here for merge and payout review:

• https://github.com/lobster-trap/Kickama/pull/323

I also rechecked the scope: the candidate diff is limited to market/orderbook/delta.go, market/orderbook/delta_test.go, and the required diagnostic pair. The committed diagnostic files are the python3 build.py generated pair for the code commit (diagnostic/build-182f71ab.json and diagnostic/build-182f71ab.logd), and I have not hand-edited the generated diagnostic output. Targeted validation passes with:

cd market && go test ./orderbook ./matching ./ws