createPatchToolCallsMiddleware

Create middleware that enforces strict tool call / tool response parity in the messages history.

Two kinds of violations are repaired:

1. Dangling tool_calls — an AIMessage contains tool_calls with no matching ToolMessage responses. Synthetic cancellation ToolMessages are injected so every tool_call has a response.
2. Orphaned ToolMessages — a ToolMessage exists whose tool_call_id does not match any tool_call in a preceding AIMessage. These are removed.

This is critical for providers like Google Gemini that reject requests with mismatched function call / function response counts (400 INVALID_ARGUMENT).

This middleware patches in two places:

1. beforeAgent: Patches state at the start of the agent loop (handles most cases)
2. wrapModelCall: Patches the request right before model invocation (handles edge cases like HITL rejection during graph resume where state updates from beforeAgent may not be applied in time)