feat: kilo gateway: elephant alpha

[Ardakilic]

This PR introduces Elephant alpha stealth drop model of kilo gateway:

https://blog.kilo.ai/p/introducing-elephant-a-new-stealth

This is the json data of the https://api.kilo.ai/api/gateway/models

{
      "id": "openrouter/elephant-alpha",
      "name": "Elephant (new)",
      "created": 1776052598,
      "description": "Elephant Alpha is a 100B-parameter text model focused on intelligence efficiency, delivering strong reasoning performance while minimizing token usage. It supports a 256K context window with up to 32K output...",
      "architecture": {
        "input_modalities": [
          "text"
        ],
        "output_modalities": [
          "text"
        ],
        "tokenizer": "Other"
      },
      "top_provider": {
        "is_moderated": false,
        "context_length": 262144,
        "max_completion_tokens": 32768
      },
      "pricing": {
        "prompt": "0",
        "completion": "0"
      },
      "context_length": 262144,
      "per_request_limits": null,
      "supported_parameters": [
        "max_tokens",
        "response_format",
        "structured_outputs",
        "temperature",
        "tool_choice",
        "tools",
        "top_p"
      ],
      "preferredIndex": 5,
      "isFree": true,
      "opencode": {

      }
    },

And I can confirm with official kilo code extension that attachments are not supported.