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- Removed outdated GitHub Actions workflows to streamline CI/CD processes.

server/nginx/default.conf

@@ -0,0 +1,22 @@
+server {
+    listen 8080;
+    server_name localhost;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Portail VitePress (fichiers statiques + clean URLs)
+    location / {
+        try_files $uri $uri/ $uri.html =404;
+    }
+
+    # Slidev : /slides/<slug> ou /slides/<slug>/ → première planche (comme static-preview.mjs)
+    # $http_host conserve le port client (reverse proxy, docker -p host:8080).
+    location ~ ^/slides/([^/]+)/?$ {
+        return 302 $scheme://$http_host/slides/$1/1$is_args$args;
+    }
+
+    # Decks Slidev : assets et routes SPA (/1, /2, …)
+    location ~ ^/slides/(?<slug>[^/]+)(?<rest>/.*)$ {
+        try_files $uri $uri/ /slides/$slug/index.html;
+    }
+}