Closes #ISSUE

The issue I ran into was that responses from anthropic compatible providers, like Kimi for Coding, have no space after data:. This change just adds a quick check to also allow for those providers to work.

Before it just resolved but did not show any output:

Now it returns the proper result:

Normal Anthropic models still work as expected:

Config to test

 "language_models": {
    "anthropic": {
      "api_url": "https://api.kimi.com/coding",
      "available_models": [
          {
            "name": "kimi-for-coding",
            "display_name": "Kimi 2.5 Coding",
            "max_tokens": 262144,
            "max_output_tokens": 32768,
          },
      ],
    },
}

TLDR:

• Accepts SSE data:{...} lines (no space) emitted by some alternative Anthropic providers, in addition to the standard data: {...} format.

Release Notes:

• Fixed Anthropic streaming for alternative providers by accepting SSE data:{...} (no space) lines.