feat(sdk-core): add withdrawFromVault() to DefiVault

[sachinBitgo]

Description

Adds withdrawFromVault() to the DefiVault SDK class, completing the ERC-4626 vault lifecycle alongside the existing depositToVault() / resumeDeposit() methods.

What changed:

• DefiVault.withdrawFromVault(params) — issues a single sendMany call with type: 'defiWithdraw' and returns { operationId, txRequestId }. The withdrawal state machine is simpler than deposit (no approve step): CREATED → WITHDRAW_TX_REQUESTED → WITHDRAW_SIGNED → WITHDRAW_CONFIRMED → COMPLETED.
• IDefiVault — new withdrawFromVault method signature; new WithdrawFromVaultOptions and WithdrawResult types exported from iDefiVault.ts.
• mpcUtils.ts — added defi-withdraw intent case. Maps SDK amount → shareTokenAmount per the DefiWithdrawIntent schema in public-types (vault share tokens, not underlying asset units).
• recipientUtils.ts — added defiWithdraw to NO_RECIPIENT_TX_TYPES (recipients/calldata are built server-side from defiParams).
• wallet.ts — added defiWithdraw case in sendMany intent dispatch.
• baseTypes.ts — added shareTokenAmount?: string to DefiIntentFields; removed clientIdempotencyKey (cleanup).
• commitlint.config.js — added DEFI- to recognized issue prefixes.
• Examples — added examples/ts/defi-vault-deposit.ts and examples/ts/defi-vault-withdraw.ts for manual staging tests.

Removed: clientIdempotencyKey from the deposit flow (not used server-side, cleaned up to reduce surface area).

Issue

DEFI-237

Type of change

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

• Unit tests added in modules/sdk-core/test/unit/bitgo/defi/defiVault.ts covering:
  • Happy path: sendMany called with correct defiWithdraw args; operationId + txRequestId returned
  • Lite apiVersion (unsignedTxs) operationId extraction path
  • Missing operationId in response throws
  • walletPassphrase forwarded correctly
  • Guard throws for missing vaultId / amount
• Manual end-to-end verified on staging using the example script (examples/ts/defi-vault-withdraw.ts)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My commits follow Conventional Commits
• The ticket DEFI-237 was included in the commit message as a reference
• I have added tests that prove my feature works
• New and existing unit tests pass locally with my changes

[linear-code]

DEFI-237