build: add helm chart for kubernetes deployment

chart/Chart.yaml

@@ -0,0 +1,16 @@
+apiVersion: v2
+name: bentopdf
+description: BentoPDF static frontend served by NGINX
+icon: https://raw.githubusercontent.com/spwoodcock/bentopdf/refs/heads/main/public/favicon.ico
+type: application
+
+# This is the chart version. This version number should be incremented each time you make changes
+# to the chart and its templates, including the app version.
+# Versions are expected to follow Semantic Versioning (https://semver.org/)
+version: 0.1.0
+
+# This is the version number of the application being deployed. This version number should be
+# incremented each time you make changes to the application. Versions are not expected to
+# follow Semantic Versioning. They should reflect the version the application is using.
+# It is recommended to use it with quotes.
+appVersion: "1.16.0"