fix(scripts): ship generate-* shims at package root for tsx drop-in

[tlgimenes]

Summary

• 5.1.1 only ships dist/scripts/*.cjs, so existing sites running tsx node_modules/@decocms/start/scripts/generate-X.ts from their build script throw ERR_MODULE_NOT_FOUND. This restores drop-in compatibility with the 5.0.x build command.
• Generator sources moved to scripts/_impl/ (build-only); 5 thin shims now live at scripts/generate-{blocks,sections,loaders,schema,invoke}.ts and `createRequire` the bundled dist/scripts/*.cjs. `tsup.config.ts` switched to named entries so output paths stay at `dist/scripts/.cjs`, and `package.json` `files` ships the 5 shim files.

Test plan

• `bun run build:js` produces `dist/scripts/generate-*.cjs` at original paths
• `bun run typecheck` clean
• `bunx tsx scripts/check-tier-boundaries.ts` clean
• `bun run test --run scripts/` — 298 tests pass
• End-to-end smoke test from a fake `node_modules/@decocms/start` layout: `tsx node_modules/@decocms/start/scripts/generate-blocks.ts ...` resolves the shim and executes the bundled CJS
• `npm pack --dry-run` confirms 5 shim files are in the tarball at `scripts/generate-*.ts`

🤖 Generated with Claude Code

---

Summary by cubic

Restores drop-in tsx execution of generator scripts from node_modules/@decocms/start/scripts/generate-*.ts by shipping thin shims at the package root. Fixes ERR_MODULE_NOT_FOUND introduced in 5.1.1 while keeping outputs at dist/scripts/*.cjs.

• Bug Fixes
  • Add five shims at scripts/generate-{blocks,sections,loaders,schema,invoke}.ts that createRequire the bundled CJS, matching 5.0.x commands like tsx node_modules/@decocms/start/scripts/generate-blocks.ts.
  • Move implementations to scripts/_impl/ and switch tsup to named entries so outputs stay dist/scripts/<name>.cjs; include the shims in package.json#files for publish.

^{Written for commit c30af54. Summary will update on new commits.}