Have CollectOSS look for and automatically read `.env`

This will make developing CollectOSS easier by allowing a developer to essentially `uv run` the CollectOSS CLI to test things out without having to muck around quite as much with environment variables

We should use `python-dotenv`'s `load_dotenv` function for this

Start at the CollectOSS CLI entry point and inspect how its runtime configuration and dependencies are declared. Use python-dotenv's load_dotenv as requested, then run the CLI with a local .env file to verify that its values are read without manually exporting environment variables.

Written by the indexing model from the issue text.