test(e2e): add placeholder check for installed binary

Verify the installed utoo is a real binary, not the placeholder script.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: elrrrrrrr

e2e/utoo-pm.ps1

@@ -263,6 +263,12 @@ try {
         throw "utoo binary not found after npm install -g"
     }
 
+    # Verify it's not a placeholder
+    $content = Get-Content $installedUtoo -Raw -ErrorAction SilentlyContinue
+    if ($content -and $content.Contains("placeholder")) {
+        throw "installed binary is still a placeholder"
+    }
+
     & $installedUtoo --version
     if ($LASTEXITCODE -ne 0) { throw "utoo --version failed" }
 

e2e/utoo-pm.sh

@@ -440,6 +440,12 @@ if [ ! -f "$INSTALLED_UTOO" ]; then
     exit 1
 fi
 
+# Verify it's not a placeholder
+if head -1 "$INSTALLED_UTOO" | grep -q "placeholder"; then
+    echo -e "${RED}FAIL: installed binary is still a placeholder${NC}"
+    exit 1
+fi
+
 "$INSTALLED_UTOO" --version
 echo -e "${GREEN}PASS: npm pack + install -g works correctly${NC}"