Scaffold StepForge: docs, license, audit, npm project

- Environment audit and stack decision in build/agent_audit.md
  (Node + Electron shell over dependency-free core; deviation recorded)
- Rewrite README/ARCHITECTURE/CONTRIBUTING for StepForge
- Add SECURITY.md threat model, CODE_OF_CONDUCT.md, CHANGELOG.md, MPL-2.0
- Replace template grep checks with structural workflow check

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

CODE_OF_CONDUCT.md

@@ -0,0 +1,24 @@
+# Code of Conduct
+
+## Our Standard
+
+Everyone participating in this project — contributors, reviewers, and users
+filing issues — is expected to:
+
+- be respectful and constructive; critique code, not people;
+- assume good faith and ask before escalating;
+- keep discussions on-topic and free of harassment, discrimination, or
+  personal attacks;
+- respect the clean-room rules in CONTRIBUTING.md when discussing other
+  products.
+
+## Enforcement
+
+Maintainers may edit, hide, or remove comments, commits, issues, and PRs that
+violate this standard, and may temporarily or permanently ban contributors
+for repeated or egregious behavior.
+
+## Reporting
+
+Report unacceptable behavior privately to the maintainers via the contact
+listed on the project page. Reports are handled confidentially.