Add CODE_OF_CONDUCT.md based on Contributor Covenant

[vgpastor]

Context

We need a Code of Conduct to set expectations for community interactions and make contributors feel welcome.

What needs to happen

• Add a CODE_OF_CONDUCT.md to the repository root
• Use the Contributor Covenant v2.1 as the base
• Update contact email to info@globalemergency.online

Acceptance criteria

• CODE_OF_CONDUCT.md added to repo root
• Contact information updated
• Link added in CONTRIBUTING.md