Environment-dependent availability of ai-delegate's local auth mode

Summary

AI delegate needs to be initialised with local mode enabled, based on the environment.

Is this a new feature?

• Yes, this is a new feature
• No, this is a change to existing functionality

Description of new functionality

The AI delegate should be initialised with local mode either enabled or disabled based on a combination of environmental factors, taking into account build mode (production/development) and an environment variable. The default will be that local mode is enabled in development builds, and disabled in production builds. An environment variable is provided to override this (allowing local mode in a production build, or disallowing it in a development one).

The docker container is always built in production mode, therefore the only way to enable local mode in the docker container will be to set the environment variable.

There are no automated tests covering this, so complete testing of each case is required before merging.

Description of existing functionality

Currently the AI delegate is initialised with local mode disabled entirely.