patchDanglingToolCalls

Patch tool call / tool response parity in a messages array.

Ensures strict 1:1 correspondence between AIMessage tool_calls and ToolMessage responses:

1. Dangling tool_calls — an AIMessage contains a tool_call with no matching ToolMessage anywhere after it. A synthetic cancellation ToolMessage is inserted immediately after the AIMessage.

2. Orphaned ToolMessages — a ToolMessage whose tool_call_id does not match any tool_call in a preceding AIMessage. The ToolMessage is removed.

Both directions are required for providers that enforce strict parity (e.g. Google Gemini returns 400 INVALID_ARGUMENT otherwise).