feat(sdk-coin-canton): added allocation request builder

[ravibitgo]

Ticket: CHALO-479

[linear-code]

CHALO-479

[Copilot]

Pull request overview

Adds support in the Canton SDK for an “AllocationRequest” txRequest (an internal/dummy transaction type) to surface DvP trade/leg details to an allocating party, including a new builder and transaction serialization support.

Changes:

• Adds TransactionType.AllocationRequest to sdk-core and wires it into Canton’s TransactionBuilderFactory.
• Introduces AllocationRequestBuilder plus a new AllocationRequest interface for representing the surfaced trade leg details.
• Extends Canton Transaction encode/decode/broadcast-json handling to support allocationRequestData payloads, and adds unit tests for the new builder.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
modules/sdk-core/src/account-lib/baseCoin/enum.ts	Adds new TransactionType.AllocationRequest.
modules/sdk-coin-canton/src/lib/allocationRequestBuilder.ts	New builder to construct/validate AllocationRequest objects.
modules/sdk-coin-canton/src/lib/iface.ts	Adds AllocationRequest interface and threads it through broadcast/json shapes.
modules/sdk-coin-canton/src/lib/index.ts	Exports AllocationRequestBuilder.
modules/sdk-coin-canton/src/lib/transactionBuilderFactory.ts	Adds factory routing for TransactionType.AllocationRequest.
modules/sdk-coin-canton/src/lib/transaction/transaction.ts	Adds storage + (de)serialization logic for allocationRequestData; treats it as dummy-signable payload.
modules/sdk-coin-canton/test/unit/builder/allocationRequest/allocationRequestBuilder.ts	New unit tests for the builder.

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