fix(widget): distinguish balance read failures from insufficient funds

[BiscuitCoder]

Which Linear task is linked to this PR?

No Linear task; external bug-fix contribution.

Why was it implemented this way?

The SDK uses LiFiErrorCode.BalanceError both for insufficient funds and for balances it cannot read. The Widget currently maps every such error to “The balance is too low” and a message claiming the requested amount remains in the wallet. An unavailable RPC, missing balance or timeout does not establish either fact.

Recognize the SDK's specific Could not read wallet balance. message within the BalanceError case and show “Could not read wallet balance” / “Your wallet balance could not be checked. Please try again.” Other balance errors and error codes retain their existing behavior.

The execution state only carries the error code and message, not a structured balance-failure reason. The check deliberately matches the SDK message exactly rather than guessing from HTTP statuses or arbitrary provider errors. Regression tests run the installed SDK's CheckBalanceTask with failing, missing, stalled and insufficient balances, then pass its serialized error fields to the Widget. This also detects a future change to the SDK message contract.

English source strings follow the repository's Crowdin workflow. No dependency changes, RPC requests or timeout changes. Includes a Widget patch changeset.

Validation:

• Before the fix: the RPC rejection, missing-balance and timeout cases failed.
• After the fix: all 281 Widget tests passed (21 files), including six new regression cases.
• Widget type check, changed-file Biome check and Changesets status passed.

Visual showcase (Screenshots or Videos)

For an SDK balance read failure:

	Before	After
Title	The balance is too low	Could not read wallet balance
Description	Transaction was not sent. 1 USDC on Ethereum remain in your wallet.	Your wallet balance could not be checked. Please try again.

A confirmed shortfall still uses the existing insufficient-balance message.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the Widget API or adds new features that require documentation, I have updated the documentation in the public-docs repository. (Not applicable: internal bug fix.)

[changeset-bot]

🦋 Changeset detected

Latest commit: 2f0b4fc

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@lifi/widget	Patch
@lifi/widget-checkout	Patch
nft-checkout	Patch
tanstack-router-example	Patch

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