:gem: [Feature] MessageViewer: Messager with role and modle name, and button

:gem: [Feature] Separate Send and Regenerate, and bind enter event to send

:gem: [Feature] Place user-interactions at bottom, and set max-height of messagers-container adjustive to page scale ratio

:gem: [Feature] Support chat with selected llm models

:recycle: [Refactor] Clean llm_requester with imports from chat_operator

:zap: [Enhance] Rename chat_renderer to chat_operator, and export functions of messager operations

:beers: [Feature] Messager and MessagerList: Manager messages and viewers

:beers: [Feature] Bind functions with enter to user input

:beers: [Feature] ChatCompletionsRequester: Use cors proxy, and hide secrets in loal

:recycle: [Refactor] Rename Concurrent Agents to LLM Mixer