add gitea action for building app container

.gitea/workflows/build.yml

@@ -0,0 +1,13 @@
+name: Build Docker containers
+on: [push]
+
+jobs:
+  Build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Build docker image
+        run: docker build -t git.arinity.org/ctmesh/map:latest .
+      - name: Push image
+        run: docker push git.arinity.org/ctmesh/map:latest