Standardize screen position naming to snake_case

- Update screen position naming from camelCase to snake_case (top_left, top_right, bottom_left, bottom_right)
- Refactor getActive route to use SCREEN_POSITIONS constant for DRY code
- Update documentation to reflect new file naming convention
- Remove unnecessary console.log for internal network requests in middleware
- Improve code maintainability and consistency across the codebase

🤖 Generated with [Claude Code](https://claude.ai/code)

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

lib/security.ts

@@ -1,6 +1,6 @@
 // Security utilities for input validation and sanitization
 
-export const VALID_SCREENS = ['large', 'left', 'right', 'topLeft', 'topRight', 'bottomLeft', 'bottomRight'] as const;
+export const VALID_SCREENS = ['large', 'left', 'right', 'top_left', 'top_right', 'bottom_left', 'bottom_right'] as const;
 export type ValidScreen = typeof VALID_SCREENS[number];
 
 // Input validation functions