fix(v1): trace Responses custom tools

[hallerite]

Summary

Parse Responses API custom_tool_call and custom_tool_call_output items into Verifiers' existing typed ToolCall and ToolMessage representation.

Codex uses custom tool items for tools such as apply_patch. The Responses dialect previously recognized only function calls, so the patch call was absent from the assistant message and its result appeared as an empty user node in saved traces.

Custom tool input is now retained as the tool-call arguments, the output is linked by call ID, and responses containing custom calls correctly report a tool-call finish reason.

Validation

• uv run pytest tests/v1/test_graph.py (7 passed)
• uv run ruff check verifiers/v1/dialects/responses.py tests/v1/test_graph.py
• pre-push markdownlint-cli2, ruff check, ruff format, and ty hooks
• live combined eval with fix(v1): keep Responses traces linear #2128: Codex 0.144.5, openai/gpt-5.5, Prime sandbox, reward 1.0
• live trace captured apply_patch as a typed assistant tool call at node 4 and its linked tool result at node 5; the subsequent shell verification and final answer were also preserved

[macroscopeapp]

Approvability

Verdict: Approved

Straightforward enhancement adding custom_tool_call support alongside existing function_call handling. Changes follow existing patterns, include test coverage, and don't modify existing behavior.

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