feat: add "OFF" option to reasoning effort dropdown #17145

Job	Run time
compile	2m 12s
knip	45s
check-translations	32s
check-openrouter-api-key	3s
platform-unit-test (ubuntu-latest)	3m 36s
platform-unit-test (windows-latest)	3m 20s
integration-test	7m 20s
	17m 48s

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