feat: Add multi-platform support and experimental features to Docker build

Dockerfile

@@ -1,9 +1,15 @@
-FROM golang:1.26-alpine as builder
+FROM --platform=$BUILDPLATFORM golang:1.26-alpine as builder
+
+ARG TARGETOS=linux
+ARG TARGETARCH
+ARG TARGETVARIANT
 
 RUN mkdir /build
 COPY . /build/
 WORKDIR /build
-RUN CGO_ENABLED=0 go build -o invertergui ./cmd/invertergui
+RUN set -eux; \
+    GOARM="${TARGETVARIANT#v}"; \
+    CGO_ENABLED=0 GOOS="${TARGETOS}" GOARCH="${TARGETARCH}" GOARM="${GOARM}" go build -o invertergui ./cmd/invertergui
 
 FROM scratch