add errors for sfa key login + update sfa demo app

[arch1995]

Motivation and Context

Jira Link: https://consensyssoftware.atlassian.net/browse/W3APD-5323

Description

Issue

• User was getting an invalid private key error as the key was not there in the session data.

Resolution

• Key was not there because the user might be using a default verifier. This PR handles these errors gracefully.

Chore

• Update the deps and code in react app sfa.

How has this been tested?

Devrels tested this.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project. (run lint)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code requires a db migration.

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Note

Medium Risk
Changes login flow behavior when useSFAKey is enabled by logging out and throwing a new/clearer sfaKeyNotFound error, and upgrades the demo app to @web3auth/modal plus React 19—both could affect connection/rehydration behavior and compatibility.

Overview
Improves error handling for SFA-key logins: when useSFAKey is enabled but the session lacks coreKitKey (e.g., default verifier), the auth connector now proactively logs out (if a session exists) and throws WalletLoginError.sfaKeyNotFound with a clearer message instead of failing later with an invalid key.

Updates the vite-react-app-sfa demo to use @web3auth/modal (instead of @web3auth/no-modal), switches the Google flow to connectTo(WALLET_CONNECTORS.AUTH, ...), adds a basic “Login with Web3Auth” button, and adjusts Web3Auth config (new clientId, sapphire_devnet, useSFAKey: true). Also bumps React/ReactDOM to 19.2.4 and enables window.global polyfill in index.html.

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Project	Deployment	Actions	Updated (UTC)
web3auth-web	Ready	Preview, Comment	Feb 11, 2026 10:32am

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Cursor Bugbot has reviewed your changes and found 2 potential issues.