Add comprehensive tests for all geo GraphQL endpoints

Created test suite covering all 8 main geo service endpoints:
- Basic: products, nodes (with filters/bounds), clusteredNodes
- Nearest: nearestHubs, nearestOffers, nearestSuppliers (with product filters)
- Routing: routeToCoordinate, autoRoute, railRoute
- Edge cases: invalid coordinates, zero radius, nonexistent UUIDs

Test suite uses real API calls to production GraphQL endpoint.
16 tests total across 4 test classes.

Files:
- tests/test_graphql_endpoints.py: Main test suite (600+ lines)
- tests/README.md: Documentation and usage guide
- pytest.ini: Pytest configuration
- run_tests.sh: Convenience script to run tests
- pyproject.toml: Added pytest and requests as dev dependencies

run_tests.sh

@@ -0,0 +1,36 @@
+#!/bin/bash
+# Run geo service GraphQL endpoint tests
+
+set -e
+
+cd "$(dirname "$0")"
+
+echo "🧪 Running Geo Service GraphQL Tests"
+echo "===================================="
+echo ""
+
+# Check if TEST_GEO_URL is set, otherwise use production
+if [ -z "$TEST_GEO_URL" ]; then
+    export TEST_GEO_URL="https://geo.optovia.ru/graphql/public/"
+    echo "📍 Testing against: $TEST_GEO_URL (production)"
+else
+    echo "📍 Testing against: $TEST_GEO_URL"
+fi
+
+echo ""
+
+# Install dependencies if needed
+if ! poetry run python -c "import pytest" 2>/dev/null; then
+    echo "📦 Installing dependencies..."
+    poetry install --with dev
+    echo ""
+fi
+
+# Run tests
+echo "🚀 Running tests..."
+echo ""
+
+poetry run pytest tests/test_graphql_endpoints.py -v -s "$@"
+
+echo ""
+echo "✅ Test run complete"