Add Windows Explorer context menu integration

- Add context menu entries for all supported file types
- Implement CLI interface with --convert and --convert-to commands
- Create installation/uninstallation scripts (registry, PowerShell, batch)
- Add NSIS installer integration for automatic context menu setup
- Support direct conversion from right-click menu
- Include comprehensive documentation and usage instructions

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

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

scripts/uninstall-context-menu.reg

@@ -0,0 +1,36 @@
+Windows Registry Editor Version 5.00
+
+; PanConverter Context Menu Uninstall Script
+; This registry file removes PanConverter context menu entries
+
+; Remove context menu for Markdown files (.md, .markdown)
+[-HKEY_CLASSES_ROOT\.md\shell\PanConverter]
+[-HKEY_CLASSES_ROOT\.md\shell\PanConverterMenu]
+
+[-HKEY_CLASSES_ROOT\.markdown\shell\PanConverter]
+
+; Remove context menu for HTML files
+[-HKEY_CLASSES_ROOT\.html\shell\PanConverter]
+[-HKEY_CLASSES_ROOT\.htm\shell\PanConverter]
+
+; Remove context menu for DOCX files
+[-HKEY_CLASSES_ROOT\.docx\shell\PanConverter]
+
+; Remove context menu for ODT files
+[-HKEY_CLASSES_ROOT\.odt\shell\PanConverter]
+
+; Remove context menu for RTF files
+[-HKEY_CLASSES_ROOT\.rtf\shell\PanConverter]
+
+; Remove context menu for LaTeX files
+[-HKEY_CLASSES_ROOT\.tex\shell\PanConverter]
+
+; Remove context menu for PDF files
+[-HKEY_CLASSES_ROOT\.pdf\shell\PanConverter]
+
+; Remove context menu for PowerPoint files
+[-HKEY_CLASSES_ROOT\.pptx\shell\PanConverter]
+[-HKEY_CLASSES_ROOT\.ppt\shell\PanConverter]
+
+; Remove context menu for OpenDocument Presentation files
+[-HKEY_CLASSES_ROOT\.odp\shell\PanConverter]