ci: initial sync with canonical/copilot-collections

[mr-cal]

@lengau is interested in experimenting with copilot collections and Imagecraft is the ideal place for him to do that.

Note that this is another experimental deployment, not the beginning of a full rollout across all our repos.

Based on canonical/snapcraft#6196

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• I've followed the contribution guidelines.
• I've signed the CLA.
• I've successfully run make lint && make test.
• I've added or updated any relevant documentation.
• In documents I changed, I added a meta description if one was missing.

[lengau]

Thanks!