execFileSync on a .cmd shim returns EINVAL on recent Node without shell:true. Same bug class as install-lefthook.mjs. Affected publint-all.ts and verify-node-next-types.ts. (cherry picked from commit 5ae40bee1c840fbbdd197ee15907aa660a343c52)
Restore explicit .ts relative specifiers in source and enable rewriteRelativeImportExtensions so emitted JS uses .js while declarations keep explicit .ts specifiers. Add a NodeNext declaration-consumer gate to prevent extensionless declaration regressions.