feat: add test isolation scripts with dynamic port discovery

- Add get-test-instance-id.sh for branch-based container isolation
- Add run-integration-tests.sh for full test lifecycle management
- Update integration tests to read service URLs from environment
  variables (GRIST_MCP_URL, MOCK_GRIST_URL) with fallback defaults

scripts/get-test-instance-id.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+# scripts/get-test-instance-id.sh
+# Generate a unique instance ID from git branch for parallel test isolation
+
+BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null || echo "unknown")
+# Sanitize: replace non-alphanumeric with dash, limit length
+echo "$BRANCH" | sed 's/[^a-zA-Z0-9]/-/g' | cut -c1-20

scripts/run-integration-tests.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+# scripts/run-integration-tests.sh
+# Run integration tests with branch isolation and dynamic port discovery
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(dirname "$SCRIPT_DIR")"
+
+# Get branch-based instance ID
+TEST_INSTANCE_ID=$("$SCRIPT_DIR/get-test-instance-id.sh")
+export TEST_INSTANCE_ID
+
+echo "Test instance ID: $TEST_INSTANCE_ID"
+
+# Start containers
+cd "$PROJECT_ROOT/deploy/test"
+docker compose up -d --build --wait
+
+# Discover dynamic ports
+GRIST_MCP_PORT=$(docker compose port grist-mcp 3000 | cut -d: -f2)
+MOCK_GRIST_PORT=$(docker compose port mock-grist 8484 | cut -d: -f2)
+
+echo "grist-mcp available at: http://localhost:$GRIST_MCP_PORT"
+echo "mock-grist available at: http://localhost:$MOCK_GRIST_PORT"
+
+# Export for tests
+export GRIST_MCP_URL="http://localhost:$GRIST_MCP_PORT"
+export MOCK_GRIST_URL="http://localhost:$MOCK_GRIST_PORT"
+
+# Run tests
+cd "$PROJECT_ROOT"
+TEST_EXIT=0
+uv run pytest tests/integration/ -v || TEST_EXIT=$?
+
+# Cleanup
+cd "$PROJECT_ROOT/deploy/test"
+docker compose down -v
+
+exit $TEST_EXIT