chore: Add git hook setup script for submodule safety

This script installs a pre-push hook that prevents pushing commits when submodules have uncommitted changes, helping avoid accidental commits with dirty submodule states.

The hook checks all submodules for uncommitted changes before allowing a push, protecting against pushing incomplete work that includes submodule modifications.

scripts/setup-git-hooks.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+# One-time setup for git hooks on this machine
+echo "🔒 Installing pre-push safety hook to prevent pushing with uncommitted submodule changes..."
+# Create pre-push hook
+mkdir -p .git/hooks
+cat >.git/hooks/pre-push <<'EOF'
+#!/bin/bash
+# Prevent pushing if submodules have uncommitted changes
+uncommitted=$(git submodule foreach --quiet 'if [ "$(git status --porcelain)" != "" ]; then echo $name; fi')
+if [ -n "$uncommitted" ]; then
+    echo "❌ ERROR: Submodules have uncommitted changes:"
+    echo "$uncommitted"
+    echo "Commit submodules first (or use git sc-commit)"
+    exit 1
+fi
+EOF
+
+echo "✅ Git hooks installed! Submodule changes will be checked before pushing."