fix: setup.sh initializes git repo if none exists

setup.sh

@@ -45,6 +45,13 @@ fi
 
 echo "[setup] Harness source: $HARNESS_SRC"
 
+# --- Ensure git repo exists ---
+if ! git rev-parse --git-dir &>/dev/null; then
+    echo "[setup] No git repo found. Initializing..."
+    git init
+    git checkout -b main 2>/dev/null || true
+fi
+
 # --- Scaffold .loop/ ---
 PROJECT_ROOT="$(pwd)"
 LOOP_DIR="$PROJECT_ROOT/.loop"