fix: canonicalize native build job names

[vigneshrajsb]

Summary

• add a shared canonical path for native build job names so truncation preserves the full build-<jobId>-<sha> suffix
• switch native build job creation to the canonical helper instead of raw .substring(0, 63) truncation
• add regression coverage for the trailing-dash case seen with subs-process-cancellations-solitary-glitter-950234

Context

• this is the same truncation class fixed in fix: canonicalize deploy job names #136, but in the native build path rather than the deploy job paths
• before this change, long deploy UUIDs could produce a job name ending in -, which Kubernetes rejects for both the Job name and generated pod-template labels

Testing

• pnpm exec jest --runInBand src/server/lib/kubernetes/tests/jobNames.test.ts src/server/lib/nativeBuild/tests/buildkit.test.ts