Enhance follow-up detection logic in RecommendationService - Added checks to differentiate between follow-up queries and new primary artist queries based on current and previous artist mentions. Updated context handling rules in ContextAwareIntentAnalyzer to clarify follow-up criteria and improve intent management. This update aims to refine user experience by ensuring accurate query handling and maintaining session context effectively.

Remove obsolete phase completion summaries and demo test scripts - Deleted `PHASE1_COMPLETION_SUMMARY.md`, `PHASE2_COMPLETION_SUMMARY.md`, `PHASE3_COMPLETION_SUMMARY.md`, and associated demo test scripts to streamline the codebase and eliminate unused documentation. This cleanup supports ongoing refactoring efforts and enhances overall project maintainability.