Create install.md

Author: qectorlab

install.md

@@ -0,0 +1,25 @@
+# Installation Guide — QECTOR Decoder v0.6.6
+
+> ⚠️ **LICENSING & COMPLIANCE NOTICE**  
+> QECTOR Decoder is **source-available**, not open source. It is free for personal, academic, and non-commercial research use.  
+> **Commercial, institutional, lab, or product-integration use requires a paid commercial license.**  
+> View pricing and request evaluation access at: **[https://qector.store/pricing](https://qector.store/pricing)**  
+> Official contact: **admin@qector.store**
+
+---
+
+## 📦 Recommended Installation (Pre-compiled Binary)
+
+The public repository serves as the Python interface, documentation, and test suite. The high-performance proprietary Rust core is **not included** in this public repository. 
+
+For all standard use cases, install the pre-compiled, optimized binary wheel directly from PyPI. This guarantees bit-identical, syndrome-faithful performance without requiring any local C++ or Rust toolchains.
+
+### 1. Create a Virtual Environment (Recommended)
+```bash
+# Windows
+py -3.11 -m venv .venv
+.\.venv\Scripts\Activate.ps1
+
+# Linux / macOS
+python3 -m venv .venv
+source .venv/bin/activate