How to use an inference snap as a dependency of another snap

Main instructions: Add a content interface with a default provider to get endpoint configuration and auto install the inference snap

subheading: Example:
1. Pick a simple chat client (super simple python hello world) - show all boilerplate
2. Highlight the slot
3. Install and show that it runs

Use the issue's main instructions as the acceptance checklist: document a content interface with a default provider, endpoint configuration, and automatic installation of the inference snap. Then cover the requested simple Python chat client, including boilerplate, slot highlighting, installation, and a demonstrated run; confirm that each of these steps is present and understandable.

Written by the indexing model from the issue text.