Add validation test for JavaScript main exports in lock files

[Copilot]

Validates that JavaScript scripts compiled into lock files export main functions and are properly packaged in custom actions.

Changes

• Added pkg/workflow/js_exports_test.go - Comprehensive validation covering:
  • Scripts used in lock files via const { main } = require('/tmp/gh-aw/actions/SCRIPT.cjs') export main
  • Setup action packages all 117 .cjs files
  • Safe-inputs/safe-outputs actions embed MCP server files correctly

Findings

All 31 scripts used in lock files already export main correctly. Helper modules (e.g., generate_footer.cjs, is_truthy.cjs) correctly export utility functions instead of main, as expected.

Test prevents regressions in the three-layer JavaScript packaging system:

1. Lock files → require main export
2. Setup action → copies all .cjs to /tmp/gh-aw/actions
3. MCP server actions → embed/copy server files

Original prompt

Review each JavaScript script compiled in the lock files and ensure it exports main function and it is packaged in the custom actions/setup.

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