Add support for OpenAI Responses API.
1. Adds a new OpenAI Model to itneract with Responses API
2. Move completions to its own file
3. Responses has a stateful and a stateless API. In this PR i have
support for both. (not streaming yet tho)
4. Responses stateful, required me to save the last message from the
model, so i had to make some minor changes to the ListStorage api.
















#### PR Dependency Tree


* **PR #120** 👈
  * **PR #121**
    * **PR #123**
      * **PR #126**

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

Adds lifecycle methods for ChatPrompt which add support for AI Plugins.
This is needed to add plugins to augment the operation of the chat
prompt.













#### PR Dependency Tree


* **PR #121** 👈
  * **PR #123**
    * **PR #126**

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

Adds support for MCP clients in an MCP plugin. Makes use of the AI
plugin system introduced in #121 .

- Added new MCP package (packages/mcp/) with AI plugin and transport
functionality
  - Updated chat prompt handling for MCP integration
- Changed token from being parsed into JWT tokens because that's not
necessarily true for many types of tokens. Github for eg, doesn't use
JWT.

This is roughly how the system works:
```mermaid
sequenceDiagram
      participant U as User
      participant CP as ChatPrompt
      participant P as MCP Plugin
      participant MCP as MCP Server
      participant M as AI Model

      U->>CP: send(input)

      CP->>P: on_build_functions(functions)
      P->>MCP: get_available_tools()
      MCP-->>P: tool_definitions
      P-->>CP: functions + mcp_tools

      CP->>M: generate_text(input, system, functions)

      alt Model calls MCP tool
          M-->>CP: function_call(mcp_tool, params)
          CP-->>M: function_result
      end

      M-->>CP: response
      CP-->>U: ChatSendResult
```






















#### PR Dependency Tree


* **PR #123** 👈
  * **PR #126**

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)