Add comprehensive Cyclomatic Complexity documentation

[Copilot]

This PR adds a comprehensive guide to Cyclomatic Complexity, addressing all aspects requested in the issue. The new documentation covers:

What's Included

Historical Context & Definition: Complete background on Thomas McCabe Sr.'s 1976 creation of the metric, including the mathematical foundation based on graph theory and practical calculation methods.

Practical Examples: Step-by-step "hello world" examples showing complexity calculations across multiple programming languages:

# Example: Simple function with complexity calculation
def greet_user_conditionally(name):
    if name:  # +1 decision point
        print(f"Hello, {name}!")
        return "Greeting sent"
    else:
        print("Hello, Anonymous!")
        return "Anonymous greeting sent"

# Cyclomatic Complexity: 2 (1 base + 1 if statement)

Tools & Integration: Comprehensive coverage of static analysis tools including:

• Python: radon, flake8-complexity, SonarQube
• JavaScript: ESLint complexity rules, complexity-report
• Java: PMD, Checkstyle
• Multi-language: Lizard, SonarQube, CodeClimate

Expert Perspectives: Detailed insights from Martin Fowler on using complexity as a guide rather than a rule, plus quotes from Robert C. Martin, Steve McConnell, and Thomas McCabe himself.

Modern AI Applications: Coverage of how cyclomatic complexity applies in the age of AI, including:

• AI-assisted code review and refactoring suggestions
• Machine learning pipeline complexity management
• Automated testing with AI systems
• Code generation optimization

Best Practices: Practical refactoring techniques with before/after examples showing how to reduce complexity through method extraction, polymorphism, and guard clauses.

The documentation follows the established repository style with clear explanations, practical code samples, real-world use cases, and authoritative references.

Fixes #88.

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