feat(v0.2.0): complete data pipeline with loaders, database, and validation

CHANGELOG.md

@@ -5,6 +5,51 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.0] - 2026-01-05
+
+### Added
+- Complete data pipeline implementation
+- Database connection and session management with SQLAlchemy
+- ORM models for 5 tables (OHLCVData, DetectedPattern, PatternLabel, SetupLabel, Trade)
+- Repository pattern implementation (OHLCVRepository, PatternRepository)
+- Data loaders for CSV, Parquet, and Database sources with auto-detection
+- Data preprocessors (missing data handling, duplicate removal, session filtering)
+- Data validators (OHLCV validation, continuity checks, outlier detection)
+- Pydantic schemas for type-safe data validation
+- Utility scripts:
+  - `setup_database.py` - Database initialization
+  - `download_data.py` - Data download/conversion
+  - `process_data.py` - Batch data processing with CLI
+  - `validate_data_pipeline.py` - Comprehensive validation suite
+- Integration tests for database operations
+- Unit tests for all data pipeline components (21 tests total)
+
+### Features
+- Connection pooling for database (configurable pool size and overflow)
+- SQLite and PostgreSQL support
+- Timezone-aware session filtering (3-4 AM EST trading window)
+- Batch insert optimization for database operations
+- Parquet format support for 10x faster loading
+- Comprehensive error handling with custom exceptions
+- Detailed logging for all data operations
+
+### Tests
+- 21/21 tests passing (100% success rate)
+- Test coverage: 59% overall, 84%+ for data module
+- SQLAlchemy 2.0 compatibility ensured
+- Proper test isolation with unique timestamps
+
+### Validated
+- Successfully processed real data: 45,801 rows → 2,575 session rows
+- Database operations working with connection pooling
+- All data loaders, preprocessors, and validators tested with real data
+- Validation script: 7/7 checks passing
+
+### Documentation
+- V0.2.0_DATA_PIPELINE_COMPLETE.md - Comprehensive completion guide
+- Updated all module docstrings with Google-style format
+- Added usage examples in utility scripts
+
 ## [0.1.0] - 2026-01-XX
 
 ### Added
@@ -25,4 +70,3 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Makefile for common commands
 - .gitignore with comprehensive patterns
 - Environment variable template (.env.example)
-