Implement missing Nutrient API tools

[msch-nutrient]

Missing Nutrient API Tools Implementation

This issue tracks the implementation of all missing tools from the Nutrient API Tools Overview.

Currently Implemented ✅

• Convert - Document format conversion
• OCR - Optical character recognition
• Watermark - Text and image watermarking
• Merge - Combine multiple documents
• Split - Extract specific pages from PDFs
• Redact - Remove sensitive text from documents

PDF Generator Tools

• PDF Generator
• PDF Creator
• PDF Writer
• URL to PDF
• PDF Form Creator
• PDF Security

PDF Editor Tools

• Duplicate PDF Pages
• Delete PDF Pages
• Flatten PDFs
• Rotate PDFs
• Add Page
• Set Page Label
• JSON Import
• XFDF Import

AI Tools

• AI Redaction

e-Signatures

• Digital Signatures

Document Optimization

• PDF Optimization
• Image Optimization
• PDF Linearization

Document Archiving

• PDF to PDF/A
• PDF/A Validation

Data Extraction

• Text Extraction
• Key-Value Pair Extraction
• Image to Text

Table Extraction

• PDF to Excel
• PDF to XML
• PDF to JSON
• PDF to CSV

Additional Tools

• PDF Annotations
• PDF Form Filling

Implementation Notes

Each tool should be implemented as a method in the NutrientDWS::Processor::Client class following the existing patterns. Each implementation should include:

1. Method implementation in lib/nutrient_dws/processor/client.rb
2. Integraation tests in spec/nutrient_dws/processor/client_spec.rb
3. Documentation updates in README.md