Prep v0.4.2 release: Korean README, hero image, channel guides #4

Job	Run time
Resolve version	5s
Generate SBOM	19s
Build linux-arm64	51s
Build osx-arm64	42s
Build win-x64	1m 41s
Build linux-x64	44s
Publish GitHub Release	14s
Publish codescan-cli to npm (manual)	0s
Submit winget manifest (manual)	-1s
Update Homebrew tap formula (manual)	-1s
	4m 34s

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