feat: SEP-2243 Mcp-Param-* mirroring — client emission + server valid… #4

Job	Run time
Spec mutex (both features must not compile)	28s
Rustdoc (deny warnings)	1m 9s
Opt-in lane (2025-11-25)	5m 17s
Default lane (2026-07-28)	4m 46s
	11m 40s

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