[1.1] Update GitHub metadata

[lorentey]

• Update pull request and issue templates
• Add workflow configuration

Initially, this simply copies the workflow from main. This is not going to work, but I'm curious to see which jobs will actually fail.

[lorentey]

CODE_OF_CONDUCT.md:13:158:* Using welcoming and inclusive language (e.g., prefer non-gendered words like “folks” to “guys”, non-ableist words like “soundness check” to “sanity check”, etc.)

Yeah, no.