feat: add themed LoginResetPassword page

[damienlethiec]

• Add LoginResetPassword.tsx with DSFR theming
• Add Storybook stories for testing (Default and WithUsernameError)
• Integrate page into KcPage router
• Use DSFR Input component with proper error handling
• Add "Back to login" link with DSFR styling
• Follow existing code patterns from LoginUpdatePassword

[LoicArc]

I don't think Keycloak will throw any error when the username/email is not found as this would be a security threat, so this may not needs to be implemented in this theme
https://cheatsheetseries.owasp.org/cheatsheets/Forgot_Password_Cheat_Sheet.html#forgot-password-request

[garronej]

I don't think Keycloak will throw any error when the username/email is not found as this would be a security threat, so this may not needs to be implemented in this theme

You're right but this is just a page you get to when you click on the "Pasword forgoten?" of the login page.

[garronej]

@damienlethiec You're the real MVP