Update CLAUDE.md with comprehensive Zephir language documentation

Expanded the documentation from basic overview to a comprehensive guide including:

**Zephir Language Guide:**
- What is Zephir: philosophy, motivations, key features
- Installation & prerequisites for Linux/Ubuntu/Debian
- Language fundamentals: file organization, syntax, variables, scope
- Complete type system: dynamic types, static types, conversions
- All operators: arithmetic, bitwise, comparison, logical, special
- Operator precedence table
- Control structures: conditionals, loops, require, let statement
- Arrays: declaration, creation, updating, appending, retrieval
- Functions: PHP function calls, parameters, dynamic invocation
- OOP: classes, methods, properties, constants, interfaces
- Closures and anonymous functions (3 syntax forms)
- Exception handling: throwing, catching, multiple types
- Built-in methods for strings, arrays, char, integer
- Complete config.json reference with all options
- Extension lifecycle: initialization and shutdown hooks
- Extension globals: configuration and access
- Static analysis features
- Custom optimizers
- Complete CLI command reference
- PHPInfo() integration

**PHPStan Integration:**
- Current CombinationsHelper implementation details
- Development workflow and best practices
- Zephir coding guidelines
- Common pitfalls and debugging tips

The document now serves as a complete reference for Zephir development
within the PHPStan Turbo Extension project.

Author: claude