feat: add Windows PowerShell installer and update README with cross-platform install instructions

Author: ualtinok

README.md

@@ -32,10 +32,13 @@
 Run the interactive setup wizard — it detects your models, configures everything, and handles compatibility:
 
 ```bash
-# One-liner install
+# macOS / Linux
 curl -fsSL https://raw.githubusercontent.com/cortexkit/opencode-magic-context/master/scripts/install.sh | bash
 
-# Or run directly with bunx/npx
+# Windows (PowerShell)
+irm https://raw.githubusercontent.com/cortexkit/opencode-magic-context/master/scripts/install.ps1 | iex
+
+# Or run directly (any OS)
 bunx @cortexkit/opencode-magic-context setup
 npx @cortexkit/opencode-magic-context setup
 ```

scripts/install.ps1

@@ -0,0 +1,27 @@
+# Magic Context — Interactive Setup (Windows)
+# Usage: irm https://raw.githubusercontent.com/cortexkit/opencode-magic-context/master/scripts/install.ps1 | iex
+
+Write-Host ""
+Write-Host "  ✨ Magic Context — Setup" -ForegroundColor Cyan
+Write-Host "  ────────────────────────"
+Write-Host ""
+
+$package = "@cortexkit/opencode-magic-context"
+
+if (Get-Command bun -ErrorAction SilentlyContinue) {
+    Write-Host "  → Using bun" -ForegroundColor Gray
+    Write-Host ""
+    & bun x $package setup
+} elseif (Get-Command npx -ErrorAction SilentlyContinue) {
+    Write-Host "  → Using npx" -ForegroundColor Gray
+    Write-Host ""
+    & npx -y $package setup
+} else {
+    Write-Host "  ✗ Neither bun nor npx found." -ForegroundColor Red
+    Write-Host ""
+    Write-Host "  Install one of:" -ForegroundColor Yellow
+    Write-Host "    • bun:  irm bun.sh/install.ps1 | iex"
+    Write-Host "    • node: https://nodejs.org"
+    Write-Host ""
+    exit 1
+}