Add Docker and Gitea workflow configurations for Talks slides deployment

- Introduced .dockerignore to exclude unnecessary files from Docker builds.
- Added build-and-push.yaml workflow for automated image building and Helm chart deployment on changes to specific paths.
- Created Dockerfile for building a static site with Nginx, including configuration for serving slides.
- Established Helm chart structure in talks-slides-dist for managing deployment configurations and resources.
- Removed outdated GitHub Actions workflows to streamline CI/CD processes.

talks-slides-dist/templates/service.yaml

@@ -0,0 +1,15 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{ include "talks-slides.fullname" . }}
+  labels:
+    {{- include "talks-slides.labels" . | nindent 4 }}
+spec:
+  type: {{ .Values.slides.service.type }}
+  ports:
+    - port: {{ .Values.slides.service.port }}
+      targetPort: http
+      protocol: TCP
+      name: http
+  selector:
+    {{- include "talks-slides.selectorLabels" . | nindent 4 }}