feat(auth): improve invalid password guidance for OAuth accounts

[kevinfernandes-hub]

Summary

Improves the error message shown when a user attempts Email + Password sign-in for an account that was originally created using another provider.

Previously, users would only see "Incorrect password", which could be confusing for accounts without a password.

This change replaces the message with:

Incorrect email or password. If you previously signed in using another provider, try using that sign-in method instead.

Motivation

Addresses issue #1313 by providing more helpful guidance while preserving existing authentication behavior and avoiding email enumeration concerns.

Changes

• Updated handling for INVALID_PASSWORD / auth/wrong-password.
• Improved the user-facing error message.
• Added tests verifying the new behavior.

Closes #1313.

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[gemini-code-assist]

Code Review

This pull request updates the wrongPassword error message to a more descriptive text advising users to try their previous sign-in method if they used another provider. This change is applied to the English (US and GB) locale files, type definitions, and various test suites. The review feedback suggests refactoring the tests to reference the enUs translation object directly rather than hardcoding the long error message string, which will improve test maintainability.