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/test-workflow-local.sh

@@ -12,13 +12,20 @@ echo "Checking Go version..."
 go version
 echo ""
 
-# Build without cgo
-echo "Building with cgo disabled..."
+# Setup library path (runtime optional)
+if [ -f "pkg/crypto/p8k/libsecp256k1.so" ]; then
+    export LD_LIBRARY_PATH="${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$(pwd)/pkg/crypto/p8k"
+    echo "Library path set for libsecp256k1.so (runtime optional)"
+fi
+echo ""
+
+# Build with pure Go + purego (no CGO needed)
+echo "Building with pure Go + purego..."
 CGO_ENABLED=0 go build -v ./...
 echo ""
 
-# Test without cgo
-echo "Testing with cgo disabled..."
+# Test with pure Go + purego
+echo "Testing with pure Go + purego..."
 CGO_ENABLED=0 go test -v $(go list ./... | xargs -n1 sh -c 'ls $0/*_test.go 1>/dev/null 2>&1 && echo $0' | grep .)
 echo ""