Improve PDF to Markdown conversion and add backend engine

.gitignore

@@ -590,3 +590,4 @@ FodyWeavers.xsd
 /build
 /.flatpak-builder
 *.traineddata
+.claude/

scripts/localpdf_studio_python/localpdf_studio_python.py

@@ -1,15 +1,15 @@
 # localpdf_studio_python.py
 # Single entry point for all LocalPDF Studio Python features.
 # Usage: localpdf_studio_python <command> [args...]
-# Commands: watermark, extract_images, convert_pdf_images, grayscale, redact
+# Commands: watermark, extract_images, convert_pdf_images, grayscale, redact, pdf_to_markdown
 
 import sys
 import json
 
 
 def main():
     if len(sys.argv) < 2:
-        print(json.dumps({"success": False, "error": "No command specified. Available: watermark, extract_images, convert_pdf_images, grayscale, redact"}))
+        print(json.dumps({"success": False, "error": "No command specified. Available: watermark, extract_images, convert_pdf_images, grayscale, redact, pdf_to_markdown"}))
         sys.exit(1)
 
     command = sys.argv[1]
@@ -31,8 +31,11 @@ def main():
     elif command == "redact":
         from redact_pdf import main as _main
         _main()
+    elif command == "pdf_to_markdown":
+        from pdf_to_markdown import main as _main
+        _main()
     else:
-        print(json.dumps({"success": False, "error": f"Unknown command: '{command}'. Available: watermark, extract_images, convert_pdf_images, grayscale, redact"}))
+        print(json.dumps({"success": False, "error": f"Unknown command: '{command}'. Available: watermark, extract_images, convert_pdf_images, grayscale, redact, pdf_to_markdown"}))
         sys.exit(1)
 
 
@@ -810,4 +813,4 @@ def _make_module(name, main_func):
 
 
 if __name__ == "__main__":
-    main()
+    main()