chore: normalize community standards (CoC + SPDX license)

CODE_OF_CONDUCT.md

@@ -1,7 +1,29 @@
-# Code of Conduct
+# Contributor Covenant Code of Conduct
 
-- Be respectful and constructive.
-- No harassment, discrimination, or abuse.
-- Keep discussions professional in issues, PRs, and reviews.
+## Our Pledge
+We pledge to make participation in our community a harassment-free experience for everyone.
 
-Maintainers may take action to preserve a safe and productive environment.
+## Our Standards
+Examples of behavior that contributes to a positive environment include:
+- Demonstrating empathy and kindness
+- Being respectful of differing opinions
+- Giving and gracefully accepting constructive feedback
+- Focusing on what is best for the community
+
+Examples of unacceptable behavior include:
+- Harassment or discriminatory language
+- Personal attacks or trolling
+- Publishing others’ private information
+- Other conduct which could reasonably be considered inappropriate
+
+## Enforcement Responsibilities
+Project maintainers are responsible for clarifying and enforcing our standards.
+
+## Scope
+This Code of Conduct applies within project spaces and in public spaces when representing the project.
+
+## Enforcement
+Report incidents via the repository security policy or maintainers.
+
+## Attribution
+This Code of Conduct is adapted from the Contributor Covenant, version 2.1.