[Feature] Plans to add model provider support

There have been many discussions in the community regarding support for multiple models.

- ChatGPTNextWeb#3484
- ChatGPTNextWeb#3923
- ChatGPTNextWeb#960
- ChatGPTNextWeb#3431
- ChatGPTNextWeb#3125

Here, we will gather NextChat's current support plans for different models and provide dynamic updates on the overall progress.

Firstly, we expect to separate the model-related logic from the frontend and may consider creating a separate JavaScript component to standardize it (this could be managed as an independent package). Afterwards, we will develop adapters for each model based on this component/package. We anticipate that each adapter will have at least the following basic capabilities: multimodality (text, images), token billing, and customizable model parameters (temperature, max_tokens, etc.).

We have roughly divided the work into the following parts:

## NextChat UI Separation
- [ ] Separation of UI components
- [ ] Allow to register model providers in Settings page
- [ ] Standardization of configuration, statistics, sharing, and other functionalities
- [ ] Standardization model features, including function calling, agents loader, etc

## Implementation of Multi-Model Providers

- [ ] Basic multi-model package (using OpenAI GPT as an example)
- [ ] Ollama
- [x] Support localhost ollama deployment( https://docs.nextchat.dev/models/ollama )
- [ ] Support manage local models
- [ ] Derivatives of GPT
- [x] Azure
- [ ] ?OneAPI (to be determined)
- [ ] Open-source models (considering support for a local App Model Manager)
- [ ] Llama
- [ ] Mistral
- [ ] Closed-source models
- [x] Claude
- [ ] AWS Lex
- [ ] Google Gemini
- [ ] Other models
- [ ] Wenxinyiyan
- [ ] Zhipu
- [ ] Hosting Platforms
- [ ] Poe.com
- [ ] together.ai
- [ ] Cloudflare AI

## Local Model Manager
- [ ] Support for local model downloading and running

## Server-Side Multi-Model Service
- [ ] Support for independently deploying a multi-model service as NextChat's API proxy

Current implementation:
- ChatGPTNextWeb#2603