feat: apply DevsLab OSS identity to devslab-examples

[jlc488]

Summary

• apply public oss-brand v0.1.1 O12 collection identity
• add EN/KO collection endorsements and GitHub header/social assets
• preserve every demo without per-demo branding changes
• add a standalone Node 22 brand CI job independent of the demo matrix

Verification

• brand checker and representative JVM demo build passed
• independent final review: spec/code/design PASS
• GraalVM nativeCompile reached AOT but Windows toolchain rejected x64 target; documented environment limitation

Canonical guide: https://devslab.kr/brand/open-source/