test: implement unit testing suite with pytest and add pre-push verification hook

scripts/hooks/pre-push

@@ -0,0 +1,18 @@
+#!/bin/sh
+# pre-push hook: runs unit tests before every git push
+# To bypass: git push --no-verify
+
+echo "🧪 Running unit tests..."
+
+uv run pytest tests/unit/ -q
+exit_code=$?
+
+if [ $exit_code -ne 0 ]; then
+    echo ""
+    echo "❌ Unit tests failed. Push aborted."
+    echo "   To bypass: git push --no-verify"
+    exit 1
+fi
+
+echo "✅ All unit tests passed."
+exit 0