refactor: update module docstrings for clarity and consistency

backend/app/schemas/souls_directory.py

@@ -1,9 +1,13 @@
+"""Schemas for souls-directory search and markdown fetch responses."""
+
 from __future__ import annotations
 
 from pydantic import BaseModel
 
 
 class SoulsDirectorySoulRef(BaseModel):
+    """Reference metadata for a soul entry in the directory index."""
+
     handle: str
     slug: str
     page_url: str
@@ -11,10 +15,14 @@ class SoulsDirectorySoulRef(BaseModel):
 
 
 class SoulsDirectorySearchResponse(BaseModel):
+    """Response wrapper for directory search results."""
+
     items: list[SoulsDirectorySoulRef]
 
 
 class SoulsDirectoryMarkdownResponse(BaseModel):
+    """Response payload containing rendered markdown for a soul."""
+
     handle: str
     slug: str
     content: str