fix(core): raise ValueError when explicit tool_outputs length mismatches tool_calls in tool_example_to_messages

[Rin (RinZ27)]

Fixes #39138

When tool_outputs is explicitly provided with a different length than tool_calls, the current zip(..., strict=False) silently produces a malformed message history — tool calls missing a paired ToolMessage, or extra outputs quietly discarded. Added a length check that raises a descriptive ValueError before the zip. Behavior when tool_outputs=None (auto-generate placeholders) is unchanged.

Release note

tool_example_to_messages now raises ValueError with a clear message when an explicitly-supplied tool_outputs list length does not match the number of tool_calls. Previously the mismatch was silently swallowed.

Verified by running the two new regression tests locally — both directions (fewer and extra outputs) raise as expected, and the original test_tool_outputs still passes.

[codspeed-hq]

Merging this PR will not alter performance

✅ 15 untouched benchmarks
⏩ 2 skipped benchmarks¹

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_{Comparing RinZ27:fix/tool-example-messages-mismatch-validation (6309077) with master (f4bc503)²}

Footnotes

1. 2 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on master (119bf69) during the generation of this report, so f4bc503 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩