docs(node-smol-builder): organize compression docs into wasm-bundle tier-3 structure

- Move cross-platform-compression.md to wasm-bundle/docs/ (tier-3)
- Move macho-compression.md to wasm-bundle/docs/ (tier-3)
- Add package-level docs/README.md with overview and links (tier-2)
- Establish clear separation between package docs (tier-2) and sub-package implementation docs (tier-3)

Author: jdalton

packages/node-smol-builder/docs/README.md

@@ -0,0 +1,41 @@
+# node-smol-builder Documentation
+
+Package-level documentation for the Socket custom Node.js binary builder.
+
+## Overview
+
+This package builds a custom Node.js v24.10.0 binary from source with Socket security patches, Brotli compression support, SEA support, and bootstrap integration.
+
+## Contents
+
+Future package-level documentation will be added here for:
+- Build process overview and configuration
+- Socket patch architecture and versioning
+- Cross-platform build considerations
+- Upstream Node.js tracking and update process
+
+## Sub-Package Documentation
+
+- **wasm-bundle/** - Rust WASM compression module
+  - [Cross-Platform Compression](../wasm-bundle/docs/cross-platform-compression.md) - WASM-based binary compression without UPX
+  - [macOS Binary Compression](../wasm-bundle/docs/macho-compression.md) - macOS-specific Mach-O compression
+
+## Quick Links
+
+- **Main README**: `../README.md`
+- **Quickstart**: `../QUICKSTART-COMPRESSION.md`
+- **Test Results**: `../TEST-RESULTS.md`
+- **Build Scripts**: `../scripts/`
+
+## Build Output
+
+- **Location**: `build/out/Release/`
+- **Files**: `node` (custom Node.js binary with Socket patches)
+- **Platforms**: Currently builds for host platform only
+
+## Upstream
+
+- **Repository**: https://github.com/nodejs/node
+- **Version**: v24.10.0
+- **Socket Patches**: `../patches/socket/`
+- **License**: MIT