feat(core-sdk): add "None" fallback strategy to transfer authorization queue (BPIP-12)

[Copilot]

encodeTransferAuthorizationEntry and executeMetaTransactionWithTokenTransferAuthorization had no way to express empty/fallback (0x) queue slots, forcing consumers of BPIP-12 commit-time meta-tx flows (createOfferAndCommit, createOfferCommitAndRedeem) to hand-roll queue encoding outside the SDK.

Changes

src/erc20/handler.ts

• Extracts SignableTransferAuthorization as an internal base type for the four signable strategies
• Adds { strategy: "None" } to UnsignedTransferAuthorization
• Reworks TransferAuthorization as an explicit discriminated union — None requires no signature fields; all other strategies retain { r, s, v, signature }
• encodeTransferAuthorizationEntry early-returns "0x" for strategy: "None", matching on-chain TokenTransferAuthorizationLib.discardNext semantics

tests/erc20/handler.test.ts

• Adds unit test asserting { strategy: "None" } encodes to "0x"
• Adds round-trip queue test for [None, ERC3009] asserting encoded output is ["0x", <strategy-1 entry>]

Usage

const queue: TransferAuthorization[] = [
  { strategy: "None" },       // leading empty slot — consumed by zero-amount seller-deposit transferFundsIn
  await signReceiveWithErc3009Authorization({ ... })  // buyer's price auth
];

await metaTx.handler.executeMetaTransactionWithTokenTransferAuthorization({
  ...args,
  transferAuthorizations: queue
});

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✅ levalleux-ludo
❌ Copilot
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[Copilot]

Pull request overview

Adds a "None" fallback strategy to the transfer authorization queue used by BPIP-12 commit-time meta-tx flows. This allows consumers to express empty/skip slots (encoded as "0x") directly via the SDK rather than hand-rolling queue encoding.

Changes:

• Extracts SignableTransferAuthorization base type and adds { strategy: "None" } variant to UnsignedTransferAuthorization / TransferAuthorization discriminated unions
• encodeTransferAuthorizationEntry early-returns "0x" for the None strategy
• Adds unit tests for the None encoding and a [None, ERC3009] round-trip

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
packages/core-sdk/src/erc20/handler.ts	Introduces None strategy in transfer authorization types and encodeTransferAuthorizationEntry
packages/core-sdk/tests/erc20/handler.test.ts	Adds tests for the new None strategy encoding behavior
package-lock.json	Lockfile churn (removes some peer deps, marks build/test deps as dev)