chore(context): refactor for consistency, optimize formatting, and simplify logic

- Cleaned up unnecessary comments in `__all__` definitions for better readability.
- Adjusted indentation and formatting across modules for improved clarity (e.g., long lines, logical grouping).
- Simplified conditional expressions and inline comments for context scoring and ranking.
- Replaced some hard-coded values with type-safe annotations (e.g., `ClassVar`).
- Removed unused imports and ensured consistent usage across test files.
- Updated `test_score_not_cached_on_context` to clarify caching behavior.
- Improved truncation strategy logic and marker handling.

backend/tests/services/context/test_adapters.py

@@ -1,11 +1,8 @@
 """Tests for model adapters."""
 
-import pytest
-
 from app.services.context.adapters import (
     ClaudeAdapter,
     DefaultAdapter,
-    ModelAdapter,
     OpenAIAdapter,
     get_adapter,
 )