Linkup research provider support

Linkup can now power web research in addition to search and contents, giving users a single Linkup-backed provider for sourced investigations. The release adds structured answer modes and investigation controls such as reasoning depth, domains, and date filters.

🚀 Features

Linkup research provider support

Linkup can now power the web_research tool in addition to web_search and web_contents.

Example configuration:

{
  "tools": {
    "research": "linkup"
  },
  "providers": {
    "linkup": {
      "credentials": {
        "api": "LINKUP_API_KEY"
      }
    }
  }
}

Research calls support Linkup's sourced-answer and structured output modes, plus mode, reasoning-depth, domain, and date filters for controlling the investigation.

By @mavam and @codex in #30.