Add .claude/skills/test-quality and reference it from AGENTS.md #3063

Job	Run time
checks / readme-snippets	11s
checks / pre-commit	49s
checks / docs	37s
checks / test (3.12, lowest-direct, windows-latest)	2m 1s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 9s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 11s
checks / test (3.11, lowest-direct, windows-latest)	1m 55s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.13, locked, ubuntu-latest)	58s
checks / test (3.13, locked, windows-latest)	1m 36s
checks / test (3.11, locked, windows-latest)	1m 37s
checks / test (3.10, lowest-direct, windows-latest)	1m 37s
checks / test (3.14, locked, ubuntu-latest)	2m 1s
checks / test (3.11, locked, ubuntu-latest)	1m 4s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 16s
checks / test (3.12, locked, ubuntu-latest)	1m 24s
checks / test (3.14, locked, windows-latest)	3m 23s
checks / test (3.14, lowest-direct, windows-latest)	1m 45s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 1s
checks / test (3.12, locked, windows-latest)	1m 38s
checks / test (3.10, locked, windows-latest)	1m 52s
checks / test (3.10, locked, ubuntu-latest)	1m 6s
checks / test (3.13, lowest-direct, windows-latest)	1m 38s
all-green	2s
	32m 59s

Provide feedback