fix(deploy): add directory creation guard and sanity check after download in installer

deploy/install.sh

@@ -43,6 +43,7 @@ else
 fi
 
 # --- 2. Workspace Setup ---
+mkdir -p "$TARGET_DIR"
 cd "$TARGET_DIR"
 
 # Download .agents/skills if missing (for curl one-liner installs)
@@ -55,6 +56,12 @@ if [ ! -d ".agents/skills" ]; then
     echo "🌐 Downloading and extracting skills archive..."
     curl -fsSL "https://git.godopu.com/tmpl/multi-agent-mux/archive/main.tar.gz" | tar -xz --strip-components=1
   fi
+  
+  if [ ! -d ".agents/skills" ]; then
+    echo "❌ Error: Fetch completed but '.agents/skills' is still missing. Target layout might be invalid." >&2
+    exit 1
+  fi
+  echo "✅ Skills downloaded successfully."
 fi
 
 echo "📂 Ensuring metadata directory structure (.mam/)..."