Add forgejo workflow to build image

.forgejo/workflows/build.yaml

@@ -0,0 +1,24 @@
+on: [push]
+env:
+  REGISTRY: forgejo:3000
+  REGISTRY_IMAGE: forgejo:3000/Furnavia/builder
+
+jobs:
+  build:
+    runs-on: docker
+    steps:
+      -
+        name: Authenticate
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.REGISTRY_USERNAME }}
+          password: ${{ secrets.REGISTRY_TOKEN }}
+          registry: ${{ env.REGISTRY }}
+      -
+        name: Build and push
+        uses: docker/build-push-action@v6
+        with:
+          push: true
+          tags:
+            ${{ env.REGISTRY_IMAGE }}:${{ github.ref_name }}
+            ${{ env.REGISTRY_IMAGE }}:latest