fix(onboarding): recovery phrase corruption via PIN mismatch

[bakoushin]

Description

When a user taps "Create Account", sets PIN A, and proceeds to cloud backup setup, the account is created with secrets encrypted using PIN A. If the user then navigates back to Welcome (e.g. backup setup fails) and taps "Create Account" again, they go through PincodeSet a second time and can set a different PIN B. The old getOrCreateAccount() silently returned the existing account because it found one in Redux state, but PIN B is now cached in memory. All secrets remain encrypted with PIN A. Every subsequent operation that decrypts the mnemonic or private key uses the wrong password leading to corrupted mnemonic readings.

Reproduction

Ensure Cloud Backup is enabled.

1. Tap "Create Account", set PIN A (e.g. 111112), proceed to cloud backup setup
2. Don't set up the cloud backup, navigate back to Welcome
3. Tap "Create Account" again, set a different PIN B (e.g. 111113)
4. Proceed to cloud backup, choose "Sign in another way" and tap "Continue" to reveal the recovery phrase.

Corrupted recovery phrase

Fix

Instead of relying on whether an account already exists in state, we now rely on user intent. If the user chose "Create Account", we always clean up stale keychain entries and create a fresh account -- regardless of what might be left over from a previous attempt.

If the user chose to restore, we skip account creation entirely, since restore flows (seed phrase import, cloud backup) set up the account themselves before reaching initializeAccountSaga.

Specifically:

• web3/saga.ts: Renamed getOrCreateAccount to createAccount, removed the early-return guard, and added clearStoredAccounts() at the top to wipe orphaned private key entries before creating fresh ones.
• account/saga.ts: The initializeAccountSaga checks choseToRestoreAccount to decide whether to call createAccount.

Test plan

• Updated unit test
• Tested manually against reproduction scenario
• Tested manually against restore from recovery phrase (to ensure it is not broken)

Related issues

User feedback: https://clabsco.slack.com/archives/C0A7SBUCQ12/p1770251915898519

Backwards compatibility

Y

Network scalability

NA

[MuckT]

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