fix UI/UX: Mode switch performance from 1 sec -> instant #5958

Job	Run time
test-extension (ubuntu-latest)	1m 55s
knip	1m 4s
compile	1m 17s
test-extension (windows-latest)	3m 33s
check-openrouter-api-key	1s
check-translations	41s
test-webview (ubuntu-latest)	1m 27s
test-webview (windows-latest)	2m 51s
integration-test	0s
unit-test	1s
	12m 50s

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