Add help screen, connection indicators, README and release builds (M7)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Makefile

@@ -0,0 +1,26 @@
+VERSION ?= $(shell git describe --tags --always --dirty 2>/dev/null || echo dev)
+LDFLAGS := -s -w -X main.version=$(VERSION)
+TARGETS := linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64
+
+.PHONY: build test dist clean
+
+build:
+	go build -ldflags '$(LDFLAGS)' -o arr-tui ./cmd/arr-tui
+
+test:
+	go vet ./...
+	go test ./...
+
+# Cross-compiled binaries and checksums in dist/.
+dist:
+	rm -rf dist && mkdir dist
+	@for t in $(TARGETS); do \
+		os=$${t%/*}; arch=$${t#*/}; ext=; [ $$os = windows ] && ext=.exe; \
+		echo "building $$os/$$arch"; \
+		CGO_ENABLED=0 GOOS=$$os GOARCH=$$arch go build -trimpath -ldflags '$(LDFLAGS)' \
+			-o dist/arr-tui-$$os-$$arch$$ext ./cmd/arr-tui || exit 1; \
+	done
+	cd dist && sha256sum arr-tui-* > SHA256SUMS
+
+clean:
+	rm -rf dist arr-tui