chore: rename helm chart from hightower to trebuchet

- Rename charts/hightower → charts/trebuchet
- Update Chart.yaml name field to 'trebuchet'
- Rename all helm template helpers from 'hightower.*' to 'trebuchet.*'
- Update all template files to reference trebuchet helpers
- Update values.yaml credentials secret names to use trebuchet prefix
- Update helm-release.yml workflow to:
  - Monitor charts/trebuchet/** path instead of charts/hightower/**
  - Reference correct chart path in lint and package steps
  - Remove GitHub Pages publishing (incompatible with Gitea)

Ref: FAR-132

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

charts/trebuchet/templates/temporal-service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ include "trebuchet.temporal.serviceName" . }}
+  labels:
+    {{- include "trebuchet.labels" . | nindent 4 }}
+spec:
+  selector:
+    {{- include "trebuchet.temporal.selectorLabels" . | nindent 4 }}
+  ports:
+    - name: grpc
+      port: {{ .Values.temporal.ports.grpc }}
+      targetPort: {{ .Values.temporal.ports.grpc }}
+    - name: web-ui
+      port: {{ .Values.temporal.ports.webUi }}
+      targetPort: {{ .Values.temporal.ports.webUi }}