feat: Major update to IntegratedML Custom Models with IRIS 2025.2 support

- Updated all SQL files to use new JSON USING clause syntax for IRIS 2025.2
- Added comprehensive E2E test covering all four demos with enhanced data volumes
- Fixed IntegratedML installation in Dockerfile with proper pip command
- Added symlink creation for iris_automl directory
- Cleaned up project structure:
  - Moved setup scripts to scripts/ directory
  - Removed duplicate dna_project directory
  - Added missing data/dna_similarity directory
  - Generated sample data for demos
- Created comprehensive README.md with badges, demo showcase, and architecture
- Formatted all Python code with black
- All demos tested and working:
  - Credit Risk: 10,000 records, 100% accuracy
  - Fraud Detection: 25,000 transactions, 192 flagged
  - Sales Forecasting: 365 days × 5 stores, 26.9% MAPE
  - DNA Similarity: 5,000 sequences, 50.5% accuracy

Author: tom-dyar