Implement multi-platform build system with pure Go support

- Introduced a comprehensive build system that supports multiple platforms (Linux, macOS, Windows, Android) using pure Go builds (`CGO_ENABLED=0`).
- Updated all build and test scripts to ensure compatibility with the new purego approach, allowing for dynamic loading of `libsecp256k1` at runtime.
- Added detailed documentation on the build process, platform detection, and deployment options.
- Enhanced CI/CD workflows to automate builds for all supported platforms and include necessary libraries in releases.
- Updated `.gitignore` to exclude build output files.
- Created new documentation files for deployment and multi-platform build summaries.

scripts/platform-detect.sh

@@ -0,0 +1,120 @@
+#!/bin/bash
+
+# Platform detection and binary selection helper
+# This script detects the current platform and returns the appropriate binary name
+
+detect_platform() {
+    local os=$(uname -s | tr '[:upper:]' '[:lower:]')
+    local arch=$(uname -m)
+    
+    # Normalize OS name
+    case "$os" in
+        linux*)
+            os="linux"
+            ;;
+        darwin*)
+            os="darwin"
+            ;;
+        mingw*|msys*|cygwin*)
+            os="windows"
+            ;;
+        *)
+            echo "unknown"
+            return 1
+            ;;
+    esac
+    
+    # Normalize architecture
+    case "$arch" in
+        x86_64|amd64)
+            arch="amd64"
+            ;;
+        aarch64|arm64)
+            arch="arm64"
+            ;;
+        armv7l)
+            arch="arm"
+            ;;
+        *)
+            echo "unknown"
+            return 1
+            ;;
+    esac
+    
+    echo "${os}-${arch}"
+    return 0
+}
+
+get_binary_name() {
+    local version=$1
+    local platform=$(detect_platform)
+    
+    if [ "$platform" = "unknown" ]; then
+        echo "Error: Unsupported platform" >&2
+        return 1
+    fi
+    
+    local ext=""
+    if [[ "$platform" == windows-* ]]; then
+        ext=".exe"
+    fi
+    
+    echo "orly-${version}-${platform}${ext}"
+    return 0
+}
+
+get_library_name() {
+    local platform=$(detect_platform)
+    
+    if [ "$platform" = "unknown" ]; then
+        echo "Error: Unsupported platform" >&2
+        return 1
+    fi
+    
+    case "$platform" in
+        linux-*)
+            echo "libsecp256k1-${platform}.so"
+            ;;
+        darwin-*)
+            echo "libsecp256k1-${platform}.dylib"
+            ;;
+        windows-*)
+            echo "libsecp256k1-${platform}.dll"
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+    
+    return 0
+}
+
+# If called directly, run the function based on first argument
+if [ "${BASH_SOURCE[0]}" -ef "$0" ]; then
+    case "$1" in
+        detect|platform)
+            detect_platform
+            ;;
+        binary)
+            get_binary_name "${2:-v0.25.0}"
+            ;;
+        library|lib)
+            get_library_name
+            ;;
+        *)
+            echo "Usage: $0 {detect|binary <version>|library}"
+            echo ""
+            echo "Commands:"
+            echo "  detect     - Detect current platform (e.g., linux-amd64)"
+            echo "  binary     - Get binary name for current platform"
+            echo "  library    - Get library name for current platform"
+            echo ""
+            echo "Examples:"
+            echo "  $0 detect"
+            echo "  $0 binary v0.25.0"
+            echo "  $0 library"
+            exit 1
+            ;;
+    esac
+fi
+