MCP Toolbox HTTP Source - Header Parameter don't allow headers with hyphen.

### Prerequisites

- [x] I've searched the current open issues
- [x] I've updated to the latest version of Toolbox
- [x] I've updated to the latest version of the SDK

### Toolbox version

0.28.0+Homebrew.darwin.arm64

### Environment

1. OS type and version: (output of `uname -a`) - Darwin riazs-MacBook-Pro-2.local 25.2.0 Darwin Kernel Version 25.2.0: Tue Nov 18 21:09:41 PST 2025; root:xnu-12377.61.12~1/RELEASE_ARM64_T6031 arm64
2. How are you running Toolbox:
- As a downloaded binary (e.g. from `curl -O https://storage.googleapis.com/genai-toolbox/v$VERSION/linux/amd64/toolbox`) - brew install mcp-toolbox
- As a container (e.g. from `us-central1-docker.pkg.dev/database-toolbox/toolbox/toolbox:$VERSION`)
- Compiled from source (include the command used to build)
3. Python version (output of `python --version`) - 3.12.11
4. pip version (output of `pip --version`) - 25.3

### Client

1. Client: [.](https://pypi.org/project/toolbox-langchain/)
2. Version: (`pip show `)? e.g.
- toolbox-langchain version 0.6.0
3. Example: If possible, please include your code of configuration:

```python
async with ToolboxClient("http://127.0.0.1:5000", protocol=Protocol.MCP) as toolbox:
toolbox_tools = toolbox.load_toolset()

agent = create_agent(
model,
tools=toolbox_tools,
system_prompt=(
"You are a Question Answering Agent that replies user queries from a known knowledge base"
),
middleware=[SkillMiddleware()],
checkpointer=InMemorySaver(),
)
```

```tools.yaml
anon-src:
kind: http
baseUrl:

retrieve:
kind: http
source: anon-src
method: POST
path: /get_data
headers:
Content-Type: application/json

description: Retrieve relevant content chunks from the vector database based on a query
requestBody: |
{
"message": {
"role": "user",
"content": {
"text": {{json .text}}
}
}
}
bodyParams:
- name: text
description: The query text to retrieve relevant chunks against
type: string
headerParams:
- name: X-Token
description: Application Token
type: string
- name: X-Application-ID
description: Application ID
type: string
```

### Expected Behavior

The HeaderParams work as expected in the MCP Inspector , but when loading the ToolBox using the langchain client, I expect to see similar behavior where the LLM can successfully pass the required header params, but i get a error instead - since the headers with `-` hyphen fail validation.

### Current Behavior

118 elif self.has_default:
119 default_value = self.default
--> [121](https://file+.vscode-resource.vscode-cdn.net/~/.venv/lib/python3.12/site-packages/toolbox_core/protocol.py:121) return Parameter(
122 self.name,
123 Parameter.POSITIONAL_OR_KEYWORD,
124 annotation=self.__get_type(),
125 default=default_value,
126 )

File ~/.pyenv/versions/3.12.11/lib/python3.12/inspect.py:2782, in Parameter.__init__(self, name, kind, default, annotation)
2780 is_keyword = iskeyword(name) and self._kind is not _POSITIONAL_ONLY
2781 if is_keyword or not name.isidentifier():
-> [2782](https://file+.vscode-resource.vscode-cdn.net/~/.pyenv/versions/3.12.11/lib/python3.12/inspect.py:2782) raise ValueError('{!r} is not a valid parameter name'.format(name))
2784 self._name = name

ValueError: 'X-Application-ID' is not a valid parameter name

### Steps to reproduce?

1. Create the tools.yaml file that requeires a headerParam which has hyphen in them
2. Load the tools.yml using toolbox --tools-file tools.yaml
3. load the tools server using -
4.async with ToolboxClient("http://127.0.0.1:5000", protocol=Protocol.MCP) as toolbox:
toolbox_tools = toolbox.load_toolset()
5. The Step 4, leads to the error above.
...

### Additional Details

_No response_