Add .claude/skills/test-quality and reference it from AGENTS.md #3062

Job	Run time
checks / docs	33s
checks / pre-commit	51s
checks / readme-snippets	12s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.11, locked, ubuntu-latest)	1m 2s
checks / test (3.12, lowest-direct, windows-latest)	1m 44s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 15s
checks / test (3.10, lowest-direct, windows-latest)	1m 57s
checks / test (3.10, locked, windows-latest)	1m 44s
checks / test (3.10, locked, ubuntu-latest)	1m 13s
checks / test (3.11, lowest-direct, windows-latest)	1m 44s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 5s
checks / test (3.11, locked, windows-latest)	1m 21s
checks / test (3.13, locked, ubuntu-latest)	59s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 5s
checks / test (3.12, locked, ubuntu-latest)	1m 28s
checks / test (3.14, locked, windows-latest)	2m 19s
checks / test (3.13, lowest-direct, windows-latest)	1m 41s
checks / test (3.14, locked, ubuntu-latest)	2m 8s
checks / test (3.13, locked, windows-latest)	1m 36s
checks / test (3.14, lowest-direct, windows-latest)	1m 38s
checks / test (3.12, locked, windows-latest)	1m 45s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 4s
all-green	5s
	31m 37s

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