Feat: Refactor handlePassword method to call authenticateUser

Replaced the postVerificationProcesses function with authenticateUser in the handlePassword method for better code clarity and functionality. This update includes extracting several helper methods to modularize the authentication steps, like verifyPassword, processUserFound, and cache handling functions. Also, added a new constant for the Redis user cache prefix and ensured consistent naming across the codebase.

Signed-off-by: Christian Roessner c@roessner.co