add Docker and CI/CD pipeline with ledo

Configure Next.js static export with nginx serving, Dockerfile
(multi-stage build), docker-compose for prod/dev, Gitea Actions
pipelines for build-on-push and tag-based releases using ledo tool.

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

docker/docker-compose.yml

@@ -0,0 +1,11 @@
+version: "3.7"
+services:
+  site:
+    image: git.cynarski.pl/automancer/site:latest
+    ports:
+      - "8080:8080"
+    networks:
+      - network-automancer-dev
+
+networks:
+  network-automancer-dev: {}