Integrate web search citations with llm schema

[ar-jan]

Web search via API was just made available.

[ar-jan]

Implemented in #22, I'll use this issue to track processing web search citations by llm per simonw/llm#716. Currently stored in the response_json column.

"venice_parameters": {
    "web_search_citations": [
      {
        "title": "What is Brave Search? | Brave",
        "url": "https://brave.com/search/",
        "content": "AI-powered answers; results you actually want, served from an independent index; and real privacy. On mobile, desktop, and anywhere the web takes you, Brave Search is the real alternative to Google."
      },
      ...
      }
    ]
  }