style: normalize code formatting across the codebase

- Standardize quote style (single to double quotes)
- Improve code formatting consistency
- Apply formatting to utilities, GUI components, and tools
- Update imports and docstrings for consistency

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

config/defaults.py

@@ -10,7 +10,7 @@ from config.schema import (
     DatabaseConfig,
     PathConfig,
     ExtractionConfig,
-    AppConfig
+    AppConfig,
 )
 
 
@@ -43,7 +43,7 @@ DEFAULT_APP_CONFIG = AppConfig(
         verbose=True,
         auto_convert=True,
         merge_batches=True,
-    )
+    ),
 )