Add Forgejo CI workflow

Verify job compiles and tests the Go side with a stubbed dist/, which
main.go embeds and the frontend build produces. Binary job builds the UI
and the real binary.

Living in .forgejo/workflows means Forgejo uses this instead of the 23
upstream .github workflows, which need GitHub-only runner labels.

.forgejo/workflows/build.yml

@@ -0,0 +1,73 @@
+name: Build
+
+# Forgejo bevorzugt .forgejo/workflows gegenüber .github/workflows. Die 23
+# Upstream-Workflows laufen hier also nicht mit — die verlangen ohnehin
+# GitHub-spezifische Runner-Label (depot-ubuntu-24.04-arm) und Secrets.
+
+on:
+  push:
+    branches: [master]
+  workflow_dispatch:
+
+jobs:
+  verify:
+    name: Go build & test
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      # main.go bindet dist/ per //go:embed ein. Das Verzeichnis wird vom
+      # Frontend-Build erzeugt und ist gitignored — für den reinen Compile-Check
+      # reicht ein Platzhalter, go:embed braucht nur mindestens eine Datei.
+      - name: Stub embedded assets
+        run: mkdir -p dist && echo stub > dist/index.html
+
+      - name: Build
+        run: go build ./...
+
+      - name: Vet
+        run: go vet ./util/sponsor/... ./charger/... ./core/... ./server/...
+
+      - name: Test
+        run: CGO_ENABLED=0 go test ./...
+
+  binary:
+    name: evcc binary
+    runs-on: ubuntu-latest
+    needs: verify
+
+    steps:
+      # fetch-depth 0: das Makefile leitet VERSION aus git describe --tags ab
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 26
+          cache: npm
+
+      - name: Install UI deps
+        run: npm ci
+
+      - name: Build UI
+        run: make ui
+
+      - name: Build binary
+        run: make build
+
+      - uses: actions/upload-artifact@v3
+        with:
+          name: evcc
+          path: evcc