refactor: move V1 code into v1/ subdirectory

- git mv cmd/ internal/ pkg/ test/ go.mod go.sum Makefile build.sh docs/ v1/
- Create v1/README.md with V1 documentation
- Update root README for V1 + V2 structure
- V1 still builds (cd v1 && go build ./cmd/hostkeeper) and 105 tests pass
- Root is now clean for V2 development

v1/build.sh

@@ -0,0 +1,48 @@
+#!/bin/bash
+# Build script for multiple platforms
+set -e
+
+VERSION=${VERSION:-$(git describe --tags --always --dirty 2>/dev/null || echo "dev")}
+BUILD_DIR=${BUILD_DIR:-"build"}
+BINARY_NAME="hostkeeper"
+
+echo "Building Hostkeeper v${VERSION}"
+echo "━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
+
+rm -rf ${BUILD_DIR}
+mkdir -p ${BUILD_DIR}
+
+platforms=(
+    "linux/amd64"
+    "linux/arm64"
+    "linux/arm"
+    "darwin/amd64"
+    "darwin/arm64"
+    "windows/amd64"
+)
+
+for platform in "${platforms[@]}"; do
+    IFS='/' read -r os arch <<< "$platform"
+
+    output_name="${BINARY_NAME}-${os}-${arch}"
+    if [ "$os" = "windows" ]; then
+        output_name="${output_name}.exe"
+    fi
+
+    echo "  Building for ${os}/${arch}..."
+
+    GOOS=$os GOARCH=$arch go build \
+        -ldflags "-X main.version=${VERSION} -X main.buildTime=$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
+        -o "${BUILD_DIR}/${output_name}" \
+        ./cmd/hostkeeper
+
+    if command -v shasum &> /dev/null; then
+        (cd ${BUILD_DIR} && shasum -a 256 "${output_name}" > "${output_name}.sha256")
+    fi
+done
+
+echo ""
+echo "Build complete! Binaries in ${BUILD_DIR}/"
+echo ""
+echo "Available binaries:"
+ls -lh ${BUILD_DIR}/