Add comprehensive documentation on software architecture patterns

[Copilot]

This PR adds a comprehensive guide to software architecture patterns to address the question "What are the different types of architecture patterns?" raised in the issue.

What's Added

Created a new architecture-patterns.md document that covers 13 essential software architecture patterns:

• Layered Architecture (N-tier) - Traditional horizontal layer organization
• Microservices Architecture - Small, independent services approach
• Service-Oriented Architecture (SOA) - Enterprise-level service-based design
• Event-Driven Architecture - Asynchronous event-based communication
• Hexagonal Architecture (Ports and Adapters) - Isolation of business logic
• Clean Architecture - Framework-independent layered approach
• Model-View-Controller (MVC) - Classic UI separation pattern
• Model-View-ViewModel (MVVM) - Data binding focused UI pattern
• Repository Pattern - Data access abstraction
• CQRS - Command Query Responsibility Segregation
• Event Sourcing - Event-based state management
• Pipe and Filter - Sequential data processing
• Publish-Subscribe - Decoupled messaging pattern

Content Structure

Each pattern includes:

• Clear description and key concepts
• When to use the pattern
• Pros and cons analysis
• Practical guidance for implementation decisions

The document also includes guidance on choosing the right pattern based on application requirements, team structure, and technical constraints.

Additionally updated the README.md to reference the new documentation, maintaining the repository's purpose as a learning journal.

Fixes #22.

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