feat: add TypeScript definitions for imageProcessing options

- Add imageProcessing interface with maxRetries and verboseLogging properties
- Keep preprocessing lowercase to match actual implementation
- TypeScript definitions now correctly reflect the implementation in constants.js

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

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

Author: nicolasiscoding

index.d.ts

@@ -70,6 +70,10 @@ declare namespace HTMLtoDOCX {
         preprocessing?: {
             skipHTMLMinify?: boolean;
         };
+        imageProcessing?: {
+            maxRetries?: number;
+            verboseLogging?: boolean;
+        };
     }
 }