feat(auth): surface GIdP password policy violations with actionable error messages

[demolaf]

Closes #2128.

When Google Identity Platform password policy enforcement is enabled, the Firebase Auth SDK returns a PASSWORD_DOES_NOT_MEET_REQUIREMENTS error with the specific failing constraints.

Previously FirebaseUI silently swallowed these errors — users saw nothing or a generic "unknown error" dialog.

Changes

• Adds AuthException.PasswordPolicyViolationException with a human-readable message and the list of failing requirements
• Detects PASSWORD_DOES_NOT_MEET_REQUIREMENTS in both FirebaseAuthWeakPasswordException.reason and the raw FirebaseException message (actual type from SDK 24.0.1+)
• Fixes subclass ordering in AuthException.from() so FirebaseAuthWeakPasswordException is no longer matched as InvalidCredentialsException
• Surfaces the policy message in ErrorRecoveryDialog with a "Try again" action
• Fixes the silent catch {} in EmailAuthScreen.onSignUpClick that was discarding all sign-up errors

NOTE: If passwordValidationRules in AuthUIConfiguration doesn't match the policy configured in the
Firebase console, the client-side check won't catch the weak password before submission and this exception
will be thrown instead.

Expected Behavior

[gemini-code-assist]

Code Review

This pull request introduces support for Google Identity Platform password policy requirements. It adds a new PasswordPolicyViolationException class, updates exception mapping in AuthException.from to parse password policy requirements from FirebaseAuthWeakPasswordException, handles exceptions in EmailAuthScreen, and adds comprehensive unit tests. The review feedback suggests making the bracket parsing in parsePasswordPolicyRequirements more robust by searching relative to the policy substring, and specifying a locale (such as Locale.US) when calling uppercase() to avoid locale-specific string transformation issues.