Add SSE response mode to the 2026 streamable-HTTP server entry #3120

Job	Run time
checks / docs	31s
checks / pre-commit	54s
checks / readme-snippets	11s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 13s
checks / test (3.10, locked, ubuntu-latest)	1m 14s
checks / test (3.11, locked, windows-latest)	1m 37s
checks / test (3.11, lowest-direct, windows-latest)	1m 35s
checks / test (3.11, locked, ubuntu-latest)	1m 12s
checks / test (3.10, locked, windows-latest)	1m 45s
checks / test (3.12, locked, windows-latest)	1m 42s
checks / test (3.14, locked, windows-latest)	2m 37s
checks / test (3.13, lowest-direct, windows-latest)	1m 44s
checks / test (3.12, locked, ubuntu-latest)	1m 11s
checks / test (3.13, locked, ubuntu-latest)	1m 2s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 5s
checks / test (3.12, lowest-direct, windows-latest)	1m 38s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.10, lowest-direct, windows-latest)	1m 34s
checks / test (3.14, lowest-direct, windows-latest)	1m 39s
checks / test (3.13, locked, windows-latest)	1m 37s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 2s
checks / test (3.14, locked, ubuntu-latest)	2m 10s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 17s
all-green	3s
	31m 41s

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