feat(e2e): add DSL support to TestActionPlanner and create E2ECli

- Modify TestActionPlanner to support DSL format for scenario generation
- Add SimpleDslParser for parsing DSL in mpp-core
- Add useDslFormat option to PlannerConfig (default: true)
- Create E2ECli for AI-driven E2E test scenario generation
- Add runE2ECli Gradle task

Usage:
./gradlew :mpp-ui:runE2ECli -Pe2eUrl="https://example.com" -Pe2eGoal="Login with valid credentials"

Related to #532

Author: phodal