feat: add Helm chart and release workflow

Adds a Helm chart under charts/hightower/ as an alternative to the
Flux/Kustomize deployment. Distributed via GitHub Pages (gh-pages branch).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

charts/hightower/Chart.yaml

@@ -0,0 +1,6 @@
+apiVersion: v2
+name: hightower
+description: API-driven AI pentester built on Shannon, deployed as a service on Kubernetes
+type: application
+version: 0.1.0
+appVersion: "1.0.0"