Propagate contextvars.Context through anyio streams without modifying SessionMessage #1722

Job	Run time
checks / pre-commit	31s
checks / test (3.10, lowest-direct, windows-latest)	2m 29s
checks / test (3.13, lowest-direct, windows-latest)	3m 2s
checks / test (3.13, locked, windows-latest)	2m 34s
checks / test (3.11, locked, windows-latest)	2m 12s
checks / test (3.12, lowest-direct, ubuntu-latest)	55s
checks / test (3.12, locked, windows-latest)	3m 37s
checks / test (3.10, locked, windows-latest)	2m 9s
checks / test (3.13, locked, ubuntu-latest)	47s
checks / test (3.13, lowest-direct, ubuntu-latest)	55s
checks / test (3.11, locked, ubuntu-latest)	48s
checks / test (3.12, lowest-direct, windows-latest)	3m 35s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 18s
checks / test (3.14, lowest-direct, windows-latest)	2m 34s
checks / readme-snippets	12s
checks / test (3.10, lowest-direct, ubuntu-latest)	54s
checks / test (3.10, locked, ubuntu-latest)	51s
checks / test (3.14, locked, windows-latest)	2m 43s
checks / test (3.11, lowest-direct, ubuntu-latest)	51s
checks / test (3.12, locked, ubuntu-latest)	56s
checks / test (3.11, lowest-direct, windows-latest)	2m 28s
checks / test (3.14, locked, ubuntu-latest)	2m 14s
all-green	4s
	38m 39s

Provide feedback