Automatically load streams on accessor

[bruno-f-cruz]

Fixes #78

[Copilot]

Pull Request Overview

This PR implements automatic loading of data streams when accessed, controlled by a new implicit_loading context manager. By default, streams will auto-load when their data is accessed, eliminating the need to explicitly call load() in most cases. Users can disable this behavior when needed by using implicit_loading(False).

Key changes:

• Added implicit_loading context manager using contextvars for thread-safe state management
• Modified data access to automatically trigger loading when implicit loading is enabled
• Refactored internal naming from _hashmap to _data_stream_mapping for clarity
• Enhanced test coverage for implicit loading scenarios including error handling and nested collections

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
src/contraqctor/contract/base.py	Implements implicit loading mechanism with context manager and updates data access logic to auto-load streams
tests/test_contract/test_core.py	Adds comprehensive tests for implicit loading behavior in various scenarios including nested collections and error states

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.