HarnessAgent now supports image inputs for all harness adapters

The AI SDK HarnessAgent layer now accepts image inputs across every harness adapter.

Pass images alongside text in the standard AI SDK message format: a content array mixing { type: 'text' } and { type: 'file' } parts.

Image input is processed by the harnesses' underlying vision models and supported across all available adapters: Claude Code, Cline, Codex, Cursor, Deep Agents, fx, GitHub Copilot, Grok Build, OpenCode, Pi.