v0.3.7: harden bundled CadCore v0.12.3 delivery

[KiYouJyo]

This PR hardens the bundled/default CadCore delivery path in SpatialViewer v0.3.7. It is not the explanation for the reported real-drawing defects: the user has confirmed through the in-app kernel manager that CadCore v0.12.3 was already manually activated when those defects were reproduced.

Changes:

• advance external/SpatialViewer.CadCore to published CadCore v0.12.3 commit 2f150fbdcf380fba6f60df7f8a41361322afdd8f
• set source-build CadCoreBundledVersion to 0.12.3
• make v0.3.7 acceptance fail if source gitlink/version are not exactly v0.12.3
• require latest-integrated resolution to resolve that exact v0.12.3 release
• unpack the final MSIXBundle and SHA-256 compare all five bundled CadCore assemblies byte-for-byte with the published v0.12.3 payload
• keep trilingual release notes explicit that the three real-drawing defects are still unresolved until validated on the original failing DWG
• update v0.3.7 release metadata so future fresh installs/source builds carry v0.12.3 by default

Important correction: the About/Update UI reports CadCoreRuntimeBootstrapper.CurrentVersion, and external kernels are activated during the module initializer before later CAD/XAML references bind. Therefore a restarted app showing current Cad Core v0.12.3 is meaningful evidence that the manually installed v0.12.3 candidate was selected. The remaining long rogue lines, title-block text fidelity, and axis/dimension style defects must be treated as v0.12.3 kernel defects, not dismissed as an old-kernel packaging issue.