Update CHANGELOG.md with Agent Analysis feature documentation

Author: Bob Strahan

CHANGELOG.md

@@ -9,14 +9,23 @@ SPDX-License-Identifier: MIT-0
 
 ### Added
 
+- **Agent Analysis Feature for Natural Language Document Analytics**
+  - Added integrated AI-powered analytics agent that enables natural language querying of processed document data
+  - **Key Capabilities**: Convert natural language questions to SQL queries, generate interactive visualizations and tables, explore database schema automatically
+  - **Secure Architecture**: All Python code execution happens in isolated AWS Bedrock AgentCore sandboxes, not in Lambda functions
+  - **Multi-Tool Agent System**: Database discovery tool for schema exploration, Athena query tool for SQL execution, secure code sandbox for data transfer, Python visualization tool for charts and tables
+  - **Example Use Cases**: Query document processing volumes and trends, analyze confidence scores and extraction accuracy, explore document classifications and content patterns, generate custom charts and data tables
+  - **Sample W2 Test Data**: Includes 20 synthetic W2 tax documents for testing analytics capabilities
+  - **Configurable Models**: Supports multiple AI models including Claude 3.7 Sonnet (default), Claude 3.5 Sonnet, Nova Pro/Lite, and Haiku
+  - **Web UI Integration**: Accessible through "Document Analytics" section with real-time progress display and query history
+
 - **Automatic Glue Table Creation for Document Sections**
   - Added automatic creation of AWS Glue tables for each document section type (classification) during processing
   - Tables are created dynamically when new section types are encountered, eliminating manual table creation
   - Consistent lowercase naming convention for tables ensures compatibility with case-sensitive S3 paths
   - Tables are configured with partition projection for efficient date-based queries without manual partition management
   - Automatic schema evolution - tables update when new fields are detected in extraction results
 
-
 ## [0.3.9]
 
 ### Added