build: add Makefile release-arm64 target for local Docker-based arm64 build

Woodpecker 0.15.4 does not support per-step agent platform routing —
when: platform: is evaluated at compile time against the server and
drops the step entirely. Use 'make release-arm64 GOGS_TOKEN=<token>'
on the local aarch64 machine to build and upload arm64 artifacts.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Makefile

@@ -0,0 +1,49 @@
+GOGS_API   := http://172.0.0.29:3000/api/v1
+GOGS_REPO  := sarman/tftsr-devops_investigation
+TAG        ?= v0.1.0-alpha
+TARGET     := aarch64-unknown-linux-gnu
+
+# Build linux/arm64 release artifact natively inside a Docker container,
+# then upload to the Gogs release for TAG.
+.PHONY: release-arm64
+release-arm64: build-arm64 upload-arm64
+
+.PHONY: build-arm64
+build-arm64:
+	docker run --rm \
+		--platform linux/arm64 \
+		-v "$(CURDIR):/workspace" \
+		-w /workspace \
+		rust:1.88-slim \
+		bash -c ' \
+			apt-get update -qq && \
+			apt-get install -y -qq libwebkit2gtk-4.1-dev libssl-dev libgtk-3-dev \
+				libayatana-appindicator3-dev librsvg2-dev patchelf pkg-config curl perl && \
+			curl -fsSL https://deb.nodesource.com/setup_22.x | bash - && \
+			apt-get install -y nodejs && \
+			npm ci --legacy-peer-deps && \
+			rustup target add $(TARGET) && \
+			cargo install tauri-cli --version "^2" --locked && \
+			CI=true cargo tauri build --target $(TARGET) && \
+			mkdir -p artifacts/linux-arm64 && \
+			find src-tauri/target/$(TARGET)/release/bundle \
+				-name "*.deb" -o -name "*.rpm" -o -name "*.AppImage" | \
+				xargs -I{} cp {} artifacts/linux-arm64/ \
+		'
+	@echo "Artifacts:"
+	@ls -lh artifacts/linux-arm64/
+
+.PHONY: upload-arm64
+upload-arm64:
+	@test -n "$(GOGS_TOKEN)" || (echo "ERROR: set GOGS_TOKEN env var"; exit 1)
+	@RELEASE_ID=$$(curl -sf "$(GOGS_API)/repos/$(GOGS_REPO)/releases/tags/$(TAG)" \
+		-H "Authorization: token $(GOGS_TOKEN)" | \
+		grep -o '"id":[0-9]*' | head -1 | cut -d: -f2); \
+	echo "Release ID: $$RELEASE_ID"; \
+	for f in artifacts/linux-arm64/*; do \
+		[ -f "$$f" ] || continue; \
+		echo "Uploading $$f..."; \
+		curl -sf -X POST "$(GOGS_API)/repos/$(GOGS_REPO)/releases/$$RELEASE_ID/assets" \
+			-H "Authorization: token $(GOGS_TOKEN)" \
+			-F "attachment=@$$f;filename=$$(basename $$f)" && echo "OK" || echo "FAIL: $$f"; \
+	done