feat: add flexible retryable ticket encoding primitive

[gomesalexandre]

closes #639

what

Adds ParentToChildMessageCreator.encodeRetryableTicket, a static primitive that encodes the Inbox createRetryableTicket calldata and computes the fee math without estimating gas against the child chain. gasLimit and maxFeePerGas are passed directly, so it works before the child chain is running - the ownership-transfer-during-Orbit-deployment scenario from the issue, where gas params are hardcoded.

const { data, deposit, maxSubmissionCost } =
  await ParentToChildMessageCreator.encodeRetryableTicket({
    to, l2CallValue, data, excessFeeRefundAddress, callValueRefundAddress,
    gasLimit, maxFeePerGas, nativeTokenIsEth,
    maxSubmissionCost, // optional: read from the Inbox if omitted
  })

• maxSubmissionCost is supplied, or read from the Inbox via calculateRetryableSubmissionFee (pass parentProvider + inbox)
• deposit is supplied, or derived as gasLimit * maxFeePerGas + maxSubmissionCost + l2CallValue
• handles ETH vs ERC20 native token Inbox encoding
• returns { data, deposit, maxSubmissionCost }, no transaction request

no behavior change to getTicketCreationRequest

It is refactored to call encodeRetryableTicket after estimating gas, passing the estimated maxSubmissionCost and deposit through, so the calldata/value (including the options.deposit.base override path) are byte-identical to before.

the derived submission fee is padded

When maxSubmissionCost is read from the Inbox it is padded by submissionFeePercentIncrease (default DEFAULT_SUBMISSION_FEE_PERCENT_INCREASE = 300, the same margin the gas estimator applies). The Inbox recomputes the submission fee against block.basefee at inclusion and reverts the whole ticket-creation tx with InsufficientSubmissionCost if the baked-in value is too low. Callers wanting the raw value can pass submissionFeePercentIncrease: 0.

tests + verification

Added packages/sdk/tests/unit/encodeRetryableTicket.test.ts (ETH + ERC20 encoding decoded against the real ABI, derived deposit, caller deposit override, throw-when-underspecified). test:unit (vitest) passes; tsc, eslint, prettier --check clean.

Runtime check (offline path): deposit 1001030000000000000 (= 300000*100000000 + 0.001e18 + 1e18), selector 0x679b6ded.

---

Rebased onto the v4 monorepo restructure + L1ToL2 -> ParentToChild rename.

[CLAassistant]

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