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/app/services/context/assembly/pipeline.py

@@ -102,9 +102,7 @@ class ContextPipeline:
         self._ranker = ranker or ContextRanker(
             scorer=self._scorer, calculator=self._calculator
         )
-        self._compressor = compressor or ContextCompressor(
-            calculator=self._calculator
-        )
+        self._compressor = compressor or ContextCompressor(calculator=self._calculator)
         self._allocator = BudgetAllocator(self._settings)
 
     def set_mcp_manager(self, mcp_manager: "MCPClientManager") -> None:
@@ -336,27 +334,21 @@ class ContextPipeline:
 
         return "\n".join(c.content for c in contexts)
 
-    def _format_system(
-        self, contexts: list[BaseContext], use_xml: bool
-    ) -> str:
+    def _format_system(self, contexts: list[BaseContext], use_xml: bool) -> str:
         """Format system contexts."""
         content = "\n\n".join(c.content for c in contexts)
         if use_xml:
             return f"<system_instructions>\n{content}\n</system_instructions>"
         return content
 
-    def _format_task(
-        self, contexts: list[BaseContext], use_xml: bool
-    ) -> str:
+    def _format_task(self, contexts: list[BaseContext], use_xml: bool) -> str:
         """Format task contexts."""
         content = "\n\n".join(c.content for c in contexts)
         if use_xml:
             return f"<current_task>\n{content}\n</current_task>"
         return f"## Current Task\n\n{content}"
 
-    def _format_knowledge(
-        self, contexts: list[BaseContext], use_xml: bool
-    ) -> str:
+    def _format_knowledge(self, contexts: list[BaseContext], use_xml: bool) -> str:
         """Format knowledge contexts."""
         if use_xml:
             parts = ["<reference_documents>"]
@@ -374,9 +366,7 @@ class ContextPipeline:
                 parts.append("")
             return "\n".join(parts)
 
-    def _format_conversation(
-        self, contexts: list[BaseContext], use_xml: bool
-    ) -> str:
+    def _format_conversation(self, contexts: list[BaseContext], use_xml: bool) -> str:
         """Format conversation contexts."""
         if use_xml:
             parts = ["<conversation_history>"]
@@ -394,9 +384,7 @@ class ContextPipeline:
                 parts.append(f"**{role.upper()}**: {ctx.content}")
             return "\n\n".join(parts)
 
-    def _format_tool(
-        self, contexts: list[BaseContext], use_xml: bool
-    ) -> str:
+    def _format_tool(self, contexts: list[BaseContext], use_xml: bool) -> str:
         """Format tool contexts."""
         if use_xml:
             parts = ["<tool_results>"]