test: add ESM script build tests to publish/download suites

[kpal81xd]

Fixes #1788

Summary

• Merge separate publish/download and publish/download (contains ESM scripts) test suites into a single block using loop-based test generation over ['classic', 'esm'] script types
• Add createEsmScript helper to common.ts that waits for the server-side upload pipeline (file:set event) instead of relying on networkidle
• Add EsmBuildOptions interface and optional ESM options to downloadApp/publishApp helpers

Test plan

• Run api/basic.test.ts — verify download app (scripts: classic), publish app (scripts: classic), create ESM script, download app (scripts: esm), publish app (scripts: esm) all pass
• Run ui/basic.test.ts — verify the same test matrix passes via UI flow
• Confirm no regressions in other test suites (create/delete, export/import, navigation)

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