Create LLM Abstractions for OpenAI, Claude Opus and Google Gemini with a common base class

[rbjarnason]

Task Description
Create LLM classes for OpenAI, Claude Opus and Google Gemini, with a design that allows easy addition of other models in the future. This is a typescript based es module NodeJS modern server application.

Task Instructions
1. Create a new base chat class src/models/baseChatModel.ts in a new file.
2. Then create src/models/openAiChat.ts, src/models/claudeOpusChat.ts and src/models/googleGeminiChat.ts for chat only
3. For the cloudeOpus use the @anthropic-ai/sdk npm
4. For the googleGemini use the @google/generative-ai npm
5. For the openAi use the openai npm
6. The baseChatModel and the child classes should only implement those two methods:
generate([{role:string,message:string}], streaming: boolean | undefined, streamingCallback: Function | undefined)
getNumTokensFromMessages([{role:string,message:string}])

[rbjarnason]

Has been completed by Engineer. Fully automatically programmed: 83d7826