Add `npm run ava` command, update instructions, and exclude files from VSCode search #10447

Job	Run time
check-codeql-versions	34s
analyze-other (python)	59s
analyze-other (actions)	49s
analyze-javascript (ubuntu-22.04, linked)	4m 10s
analyze-javascript (ubuntu-24.04)	4m 10s
analyze-javascript (ubuntu-24.04, linked)	4m 10s
analyze-javascript (windows-2022, linked)	6m 18s
analyze-javascript (ubuntu-22.04)	4m 8s
analyze-javascript (windows-2022)	6m 8s
analyze-javascript (macos-14)	8m 6s
analyze-javascript (windows-2025)	5m 21s
analyze-javascript (macos-14, linked)	7m 23s
analyze-javascript (macos-15)	4m 51s
analyze-javascript (macos-13, linked)	8m 26s
analyze-javascript (macos-13)	13m 35s
analyze-javascript (macos-15, linked)	5m 34s
analyze-javascript (windows-2025, linked)	11m 3s
	1h 35m 45s

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