Add hosted electrical builder image based on kicad_auto

- Add docker/electrical-builder/Dockerfile extending setsoft/kicad_auto:ki8
- Add build_electrical_builder_image workflow to build and push to GHCR
- Update electrical_boards workflow to pull from GHCR instead of Docker Hub

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: SukuWc

.github/workflows/build_electrical_builder_image.yml

@@ -0,0 +1,47 @@
+name: build_electrical_builder_image
+
+on:
+  workflow_dispatch:
+  push:
+    paths:
+      - 'docker/electrical-builder/Dockerfile'
+
+jobs:
+  build-and-push:
+    name: Build and push electrical builder image
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Log in to GitHub Container Registry
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v5
+        with:
+          images: ghcr.io/${{ github.repository_owner }}/knot-electrical-builder
+          tags: |
+            type=raw,value=latest
+            type=sha,prefix=sha-,format=short
+
+      - name: Build and push
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: docker/electrical-builder/Dockerfile
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          cache-from: type=registry,ref=ghcr.io/${{ github.repository_owner }}/knot-electrical-builder:buildcache
+          cache-to: type=registry,ref=ghcr.io/${{ github.repository_owner }}/knot-electrical-builder:buildcache,mode=max

.github/workflows/electrical_boards.yml

@@ -13,7 +13,11 @@ jobs:
   generate-artifacts:
     name: kicad export
     runs-on: ubuntu-latest
-    container: "setsoft/kicad_auto:ki8"
+    container:
+      image: ghcr.io/${{ github.repository_owner }}/knot-electrical-builder:latest
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
     strategy:
       fail-fast: false
       matrix:

docker/electrical-builder/Dockerfile

@@ -0,0 +1 @@
+FROM docker.io/setsoft/kicad_auto:ki8