fix(mcpserver): omit unreturned TypedDict keys from structuredContent #3794

Job	Run time
checks / docs	59s
checks / pre-commit	1m 0s
checks / test (3.11, lowest-direct, windows-latest)	1m 31s
checks / test (3.11, locked, windows-latest)	1m 58s
checks / test (3.11, locked, ubuntu-latest)	1m 28s
checks / test (3.10, locked, windows-latest)	2m 10s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 10s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.12, locked, ubuntu-latest)	1m 41s
checks / test (3.12, locked, windows-latest)	1m 54s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 21s
checks / test (3.10, lowest-direct, windows-latest)	1m 33s
checks / test (3.13, locked, windows-latest)	1m 39s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 16s
checks / test (3.14, lowest-direct, windows-latest)	1m 47s
checks / test (3.14, locked, ubuntu-latest)	1m 24s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 33s
checks / test (3.12, lowest-direct, windows-latest)	1m 58s
checks / test (3.10, locked, ubuntu-latest)	1m 34s
checks / test (3.13, lowest-direct, windows-latest)	1m 55s
checks / readme-snippets	14s
checks / test (3.13, locked, ubuntu-latest)	1m 16s
checks / test (3.14, locked, windows-latest)	1m 57s
all-green	5s
	34m 45s

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