fix: wrap pipe union structured outputs #2215

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	31s
checks / test (3.10, lowest-direct, windows-latest)	2m 46s
checks / test (3.10, lowest-direct, ubuntu-latest)	56s
checks / test (3.10, locked, ubuntu-latest)	52s
checks / test (3.10, locked, windows-latest)	2m 23s
checks / test (3.11, locked, windows-latest)	2m 53s
checks / test (3.11, locked, ubuntu-latest)	47s
checks / test (3.11, lowest-direct, windows-latest)	2m 45s
checks / test (3.11, lowest-direct, ubuntu-latest)	56s
checks / test (3.12, lowest-direct, ubuntu-latest)	55s
checks / test (3.12, locked, ubuntu-latest)	53s
checks / test (3.12, lowest-direct, windows-latest)	3m 33s
checks / test (3.12, locked, windows-latest)	3m 43s
checks / test (3.13, lowest-direct, ubuntu-latest)	54s
checks / test (3.13, locked, ubuntu-latest)	46s
checks / test (3.13, lowest-direct, windows-latest)	2m 42s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 23s
checks / test (3.14, locked, ubuntu-latest)	2m 31s
checks / test (3.13, locked, windows-latest)	2m 8s
checks / test (3.14, lowest-direct, windows-latest)	2m 23s
checks / test (3.14, locked, windows-latest)	3m 33s
all-green	6s
	40m 30s

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