fix: enhance voice selection logic based on age ranges for female and male voices in synthesize_text function

fix: clarify role-play instructions and improve tone expression guidelines in get_normal_prompt functions

fix: update tax deduction limit and adjust premium calculation logic in get_user_info function

add: add unit linked mode

refactor: streamline get_normal_prompt function and enhance role-play instructions

refactor: enhance customer role-play instructions in get_normal_prompt function

fix: correct method of removing occupation from list in PersonaState

refactor: update voice selection logic for TTS synthesis

Refactor chat streaming and persona handling; enhance TTS synthesis

intial commit

fix: revert sdk_version to 5.44.1 in README.md

initial commit