Updates Jest configuration to properly handle ES module syntax:
- Switch to ts-jest/presets/default-esm preset
- Add custom resolver to map .js imports to .ts source files
- Configure extensionsToTreatAsEsm for TypeScript files
- Enable useESM in ts-jest globals
This resolves module resolution errors when running tests in
kraiken-lib which uses "type": "module" in package.json.
Fixes#85
Co-authored-by: openhands <openhands@all-hands.dev>
Reviewed-on: https://codeberg.org/johba/harb/pulls/88
