Actions:
- Checked for `.env` file existence.
- Modified `e2e/run_tests.sh` to source `.env` file if it exists, using `set -a` to export variables.
- Verified the fix by running `./e2e/run_tests.sh --dry-run` and confirming that variables from `.env` (like `LLM_BINDING=openai`) are correctly loaded.

Decisions:
- Inserted the `.env` loading logic after the default variable assignments in `e2e/run_tests.sh` to ensure `.env` values override the hardcoded defaults.
- Used `set -a` before sourcing `.env` to automatically export all variables defined in `.env`, ensuring they are available to child processes (like the Python server).

Next steps:
- None.

Lessons:
- Bash scripts often need explicit logic to load `.env` files, unlike some Python frameworks that do it automatically.
- `set -a` is a useful bash feature for loading environment files.