feat: implement missing features, update README, fix CI/CD

- Add missing CI/CD workflows (codeql, scorecard, nightly, release, weekly)
- Add missing governance files (CONTRIBUTING, CODE_OF_CONDUCT, SECURITY)
- Replace stub implementations with real logic
- Update README badges and add missing sections

Author: srpatcha

CODE_OF_CONDUCT.md

@@ -0,0 +1,4 @@
+# Code of Conduct — Contributor Covenant v2.1
+We are committed to providing a welcoming and inclusive environment.
+See: https://www.contributor-covenant.org/version/2/1/code_of_conduct.html
+Report violations to: conduct@embeddedos.org

README.md

@@ -217,3 +217,7 @@ See [CONTRIBUTING.md](CONTRIBUTING.md) for guidelines.
 ## License
 
 MIT License. See [LICENSE](LICENSE) for details.
+
+
+---
+Part of the [EmbeddedOS Organization](https://embeddedos-org.github.io).