docs: finalize concise README.md and remove verbose backup

- Remove README_OLD.md from git tracking
- Keep streamlined README.md focusing on native array capabilities
- Maintain essential documentation while improving readability

Author: greysquirr3l

README.md

@@ -123,20 +123,23 @@ counts := result.ViewCounts.Get()     // Returns []int64
 The driver supports 19 advanced DuckDB types for comprehensive analytical capabilities:
 
 ### Core Types
+
 - **Arrays**: StringArray, IntArray, FloatArray with native `Composite[T]` support
 - **JSON/Document**: JSONType for flexible document storage
 - **Precision Math**: DecimalType, HugeIntType (128-bit integers)
 - **Temporal**: IntervalType, TimestampTZType with timezone support
 - **Identifiers**: UUIDType for unique identifiers
 
 ### Advanced Types
+
 - **Structured Data**: StructType, MapType, ListType for complex hierarchies
 - **Variants**: ENUMType, UNIONType for type-safe variants
 - **Binary**: BLOBType, BitStringType for binary data
 - **Spatial**: GEOMETRYType with WKT support
 - **Performance**: QueryHintType, PerformanceMetricsType for optimization
 
 ### Usage Example
+
 ```go
 type AdvancedModel struct {
     ID        uint                `gorm:"primaryKey"`
@@ -316,4 +319,4 @@ Contributions are welcome! Please see [CONTRIBUTING.md](CONTRIBUTING.md) for gui
 
 ## Security
 
-For security issues, please see [SECURITY.md](SECURITY.md) for reporting instructions.
+For security issues, please see [SECURITY.md](SECURITY.md) for reporting instructions.