refactor: agent architecture and documentation improvements

[ceberam]

This PR includes architectural improvements and comprehensive documentation enhancements across the agent system.

Resolves #40

Commits Included

1. Enable multi-document and page-level reasoning

   • Added support for multi-document RAG queries
   • Implemented page-level reasoning as an alternative to section-level
   • Enhanced document selection capabilities

2. Refactor agent classes to inherit from ABC

   • Breaking Change: Refactored BaseDoclingAgent from Pydantic BaseModel to Python's Abstract Base Class (ABC)
   • Updated all agent classes (DoclingRAGAgent, DoclingEnrichingAgent, DoclingEditingAgent, DoclingWritingAgent, DoclingExtractingAgent, DoclingOrchestratorAgent) to inherit from ABC
   • Proper separation of concerns: ABC for agent behavior, Pydantic models for data validation only
   • Made last_operation private (_last_operation) in DoclingEnrichingAgent

3. Update uv.lock dependencies

   • Updated project dependencies

4. Documentation improvements

   • Pydantic Models: Updated all Pydantic models to use Annotated[type, Field(description="...")] pattern for better field documentation
   • Type Annotations: Added complete type annotations to all methods
   • Google-Style Docstrings: Verified and maintained Google-style docstrings across all agent modules

Testing

• All 108 tests passing
• No breaking changes to public APIs (except BaseDoclingAgent inheritance change)
• Verified backward compatibility for agent instantiation and usage

[github-actions]

✅ DCO Check Passed

Thanks @ceberam, all your commits are properly signed off. 🎉

[codecov]

Codecov Report

❌ Patch coverage is 44.80519% with 85 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
docling_agent/agent/rag.py	13.63%	76 Missing ⚠️
docling_agent/agent/enricher.py	60.00%	4 Missing ⚠️
docling_agent/agent/extractor.py	50.00%	4 Missing ⚠️
docling_agent/agent/orchestrator.py	75.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[mergify]

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[PeterStaar-IBM]

lgtm!