Add agents for dynamodb and prestosql

[TheShinriel]

Add specialized database agents for DynamoDB and PrestoSQL

✅ Type of PR

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update

��️ Description

Added two specialized database agents to help with data modeling and query design:

DynamoDB Agent - Comprehensive guide for NoSQL table design and query optimization with:

• Terminology clarification (Primary Key vs Partition Key vs Sort Key)
• Design patterns for single-table architecture and access patterns
• Query types (GetItem, Query, Scan, BatchGetItem, GSI/LSI queries)
• Write operations (PutItem, UpdateItem, DeleteItem, BatchWriteItem)
• Performance optimization strategies and common mistakes to avoid

PrestoSQL Agent - Complete guide for distributed SQL query engine with:

• Architecture concepts (Coordinator, Workers, Connectors, Catalogs)
• Table design strategies for multi-source data lakes
• Query optimization techniques and performance best practices
• Cross-catalog queries for federated data access
• Advanced SQL features (Window functions, CTEs, JSON operations)

Both agents include detailed code examples, design checklists, and common pitfalls to avoid.

��‍➡️ Behavior

• New specialized agents available for database design assistance
• DynamoDB Agent provides NoSQL modeling guidance with AWS best practices
• PrestoSQL Agent offers distributed query optimization for data lake scenarios
• Comprehensive documentation with practical examples and checklists
• Performance-focused guidance to avoid common database design mistakes
• Multi-source query support for federated data access patterns