Add comprehensive coding patterns documentation to Dev-Journal

[Copilot]

This PR adds comprehensive documentation about different coding patterns to address the question "What are the different coding patterns?" The documentation is organized into four main categories with detailed explanations, use cases, and examples.

Added Content

Design Patterns

• Creational Patterns: Singleton, Factory, Builder patterns with practical examples
• Structural Patterns: Adapter, Decorator, Facade patterns with use cases
• Behavioral Patterns: Observer, Strategy, Command patterns with implementation guidance

Architectural Patterns

• MVC/MVP/MVVM: Detailed comparison and use cases for each pattern
• Layered Architecture: Traditional n-tier architecture explanation
• Microservices: Modern distributed architecture patterns
• Event-Driven Architecture: Asynchronous communication patterns
• Hexagonal Architecture: Ports and adapters pattern for clean boundaries

Programming Paradigms

• Object-Oriented Programming: Core principles (Encapsulation, Inheritance, Polymorphism, Abstraction)
• Functional Programming: Immutability, pure functions, higher-order functions
• Procedural Programming: Traditional structured programming approach
• Reactive Programming: Stream-based asynchronous programming
• Aspect-Oriented Programming: Cross-cutting concerns management

Code Organization Patterns

• Module Pattern: Encapsulation and namespace management
• Repository Pattern: Data access abstraction
• Dependency Injection: Loose coupling through inversion of control
• Feature-Based Organization: Organizing code by business features
• Clean Architecture: Dependency rule and layered organization

Structure

The documentation is organized with a clear hierarchy:

• Main index at /coding-patterns/README.md with navigation links
• Each category has its own detailed README with explanations and examples
• Updated main repository README to include the new content section

This creates a comprehensive reference guide that developers can use to understand and implement various coding patterns in their projects.

Fixes #23.

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