doc: add roadmap to readme

README.md

@@ -152,3 +152,46 @@ pub struct Book {
 
 To read more about these features, you can refer to the [online
 documentation](https://docs.rs/georm/).
+
+## Roadmap / TODO
+
+The following features are being considered for future development:
+
+### High Priority
+- **Transaction Support**: Add comprehensive transaction support with
+  transaction-aware CRUD methods and relationship handling for atomic
+  operations across multiple entities
+- **Race Condition Fix**: Replace the current `create_or_update`
+  implementation with database-specific UPSERT operations (PostgreSQL
+  `ON CONFLICT`, MySQL `ON DUPLICATE KEY UPDATE`, SQLite `ON
+  CONFLICT`) to prevent race conditions
+
+### Medium Priority
+- **Multi-Database Support**: Extend Georm to support MySQL and SQLite
+  in addition to PostgreSQL, with database-specific optimizations and
+  dialect handling
+- **Relationship Optimization**: Implement eager loading and N+1 query
+  prevention with circular dependency protection to dramatically
+  improve performance when working with related entities
+- **Composite Primary Keys**: Add support for entities with multiple
+  primary key fields using auto-generated ID structs and type-safe
+  composite key handling
+- **Soft Delete**: Implement optional soft delete functionality with
+  `deleted_at` timestamps, allowing entities to be marked as deleted
+  without physical removal
+
+### Lower Priority
+- **Migration Support**: Add optional migration utilities that
+  leverage SQLx's existing infrastructure for schema generation,
+  verification, and evolution
+- **Enhanced Error Handling**: Consider implementing custom error
+  types with better categorization and operation context while
+  maintaining compatibility with SQLx errors
+- **Many-to-Many Relationship Improvements**: Add direct methods to
+  add or remove items from many-to-many relationships without manually
+  handling the join table
+
+### Recently Completed
+- ✅ **Defaultable Fields**: Support for fields with database defaults
+  or auto-generated values, creating companion structs with optional
+  fields for easier entity creation