[v2] Dispatcher/ServerRunner receive-path swap — replaces BaseSession #2502

Job	Run time
checks / readme-snippets	15s
checks / pre-commit	38s
checks / test (3.10, lowest-direct, windows-latest)	1m 34s
checks / test (3.10, lowest-direct, ubuntu-latest)	55s
checks / test (3.12, lowest-direct, windows-latest)	1m 29s
checks / test (3.10, locked, ubuntu-latest)	50s
checks / test (3.11, lowest-direct, ubuntu-latest)	46s
checks / test (3.12, lowest-direct, ubuntu-latest)	58s
checks / test (3.13, locked, ubuntu-latest)	46s
checks / test (3.10, locked, windows-latest)	1m 24s
checks / test (3.11, lowest-direct, windows-latest)	1m 25s
checks / test (3.13, lowest-direct, ubuntu-latest)	54s
checks / test (3.14, lowest-direct, windows-latest)	1m 50s
checks / test (3.14, locked, windows-latest)	2m 14s
checks / test (3.14, lowest-direct, ubuntu-latest)	44s
checks / test (3.13, lowest-direct, windows-latest)	1m 32s
checks / test (3.11, locked, ubuntu-latest)	47s
checks / test (3.13, locked, windows-latest)	1m 14s
checks / test (3.12, locked, ubuntu-latest)	54s
checks / test (3.11, locked, windows-latest)	1m 29s
checks / test (3.14, locked, ubuntu-latest)	1m 49s
checks / test (3.12, locked, windows-latest)	1m 19s
all-green	5s
	25m 51s

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