unit1 ex1: sync code from notebook

[belambert]

I was working through Unit 1 Exercise 1 of the smol course and noticed that the code in the notebook got a little out of sync with what's in the Markdown/HTML. I attempted to copy it over and ended up with this. I haven't looked closely at the other units and exercises yet.

I don't think I've PR'ed any Huggingface repos before, so let me know if there's anything I should do differently with PRs 😄

[Copilot]

Pull Request Overview

This PR synchronizes code examples in the Unit 1 Exercise 1 documentation with the corresponding notebook implementation. The changes add system messages with /no_think and /think directives to conversation examples and update the reasoning capabilities testing section.

• Added system messages with /no_think and /think directives to chat template examples
• Updated reasoning test code to iterate through different thinking prompts
• Fixed minor formatting inconsistencies in function parameters and code structure

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