READONLY mode support is needed in dotnet MCP server as implemented in Node version

Could you please implement support for `READONLY` mode in dotnet version?
So that when `env` configuration is configured with `"READONLY": "true"` MCP server will not allow to execute Update/Insert/Drop tools.

```
"env": {
"CONNECTION_STRING": "Server=localdev;Database=eCommerce;Integrated Security=True;TrustServerCertificate=True;Encrypt=False",
"READONLY": "true"
}
```

dotnet version:
https://github.com/Azure-Samples/SQL-AI-samples/blob/5a4ba3f8d62aa5683a497f16e5ff4c26cc600ee0/MssqlMcp/dotnet/MssqlMcp/Program.cs#L37

Node version:
https://github.com/Azure-Samples/SQL-AI-samples/blob/5a4ba3f8d62aa5683a497f16e5ff4c26cc600ee0/MssqlMcp/Node/src/index.ts#L85