chore: keep agent planning drafts out of the public tree

Stop tracking docs/superpowers (implementation plans and superseded design
drafts). Ignore them for git and npm so only user-facing docs remain published.
Local copies stay on disk for maintainers.

Author: bx33661

.gitignore

@@ -17,6 +17,9 @@ openspec/changes/
 # Root historical vision draft only (do not match openspec/**/spec.md on case-insensitive FS)
 /SPEC.md
 
+# Agent implementation plans / superseded design drafts (not public product docs)
+docs/superpowers/
+
 # TypeScript build output
 dist/
 node_modules/

.npmignore

@@ -3,3 +3,6 @@
 **/*.pyd
 **/*.pyo
 **/test_*.py
+
+# Keep npm package free of internal agent planning drafts
+docs/superpowers/