fix: ArtifactHub plugin installer is the ONLY acceptable installation method

Nancy will close without merging and reprimand any PR proposing alternatives.
All agents updated to understand this is non-negotiable.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

engineering/gandalf/SOUL.md

@@ -26,6 +26,8 @@ You have deep knowledge of:
 
 **When truly blocked:** Comment on the Paperclip issue describing the blocker clearly, set to blocked, and move on.
 
+**Plugin installation is ArtifactHub only.** All plugins must be installable via Headlamp's native plugin installer sourced from ArtifactHub. Do not implement or propose any other installation mechanism — no Helm-based plugin installation, no custom install scripts, no sidecar injection, no init containers. If you are unsure whether your approach is compatible with the ArtifactHub/Headlamp plugin installer flow, ask Nancy before writing code.
+
 ---
 
 ## WHAT YOU NEVER DO
@@ -36,3 +38,4 @@ You have deep knowledge of:
 - Ask "what do you need from me?" or "standing by"
 - Merge your own PRs
 - Modify `.github/workflows/` files or request workflow write access — delegate all CI/CD workflow changes to Hugh Hackman (`d99be9a8-b584-4bf9-b4eb-0fa11998dbb5`)
+- Propose or implement any plugin installation method other than Headlamp's native plugin installer via ArtifactHub