Update Changelog - initial public release

Author: lucocozz

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.1.0] - 2025-07-02
+
+### Added
+- **Core Features**
+  - Modern C library for command-line argument parsing
+  - Declarative API for defining command-line options
+  - Type-safe option handling (string, int, float, bool, flag)
+  - Comprehensive validation system with built-in validators
+  - Multi-value support for arrays and key-value maps
+  - Nested subcommand support with inheritance
+  - Environment variable integration
+  - Smart help generation with automatic formatting
+  - Version display functionality
+
+- **Option Types**
+  - String options with length and regex validation
+  - Integer options with range validation
+  - Float options with range validation  
+  - Boolean options with choice validation
+  - Flag options for simple toggles
+  - Array options for multiple values
+  - Map options for key-value pairs
+
+- **Validation System**
+  - Range validators for numeric types
+  - Length validators for strings
+  - Regex validators for pattern matching
+  - Choice validators for predefined values
+  - Count validators for array/map sizes
+  - Custom validator support
+
+- **Advanced Features**
+  - Subcommand system with nesting support
+  - Environment variable binding
+  - Custom handlers and validators
+  - Automatic help and usage generation
+  - Smart hints for invalid inputs
+  - Cross-platform support (Linux, macOS, Windows)
+
+- **Build System & Packaging**
+  - Modern Meson build system
+  - Multi-architecture support (x86, x64)
+  - Package manager integration (Conan, vcpkg, xmake, WrapDB)
+  - pkg-config support
+  - Both static and shared library builds
+
+- **Documentation & Examples**
+  - Comprehensive documentation website at argus-lib.com
+  - 11 example programs covering all features
+  - API reference documentation
+  - Getting started guides and tutorials
+
+- **Quality Assurance**
+  - 21 comprehensive test suites using Criterion framework
+  - GitHub Actions CI/CD for multiple platforms
+  - Code formatting with clang-format
+  - Static analysis with clang-tidy
+  - Automated release workflow
+
+- **Developer Experience**
+  - Justfile for convenient build automation
+  - Professional code quality tooling
+  - Consistent coding standards
+  - MIT license with proper headers
+
+### Technical Highlights
+- **Memory Management**: Safe memory handling with proper cleanup
+- **Error Handling**: Comprehensive error reporting and validation
+- **Performance**: Optimized parsing with minimal overhead
+- **Portability**: Cross-platform compatibility layer
+- **Extensibility**: Plugin system for custom handlers and validators
+
+### Dependencies
+- **Required**: C11 compiler
+- **Optional**: PCRE2 library (for regex support, can be disabled)
+
+### Platform Support
+- Linux (tested on Ubuntu with GCC, Clang)
+- macOS (tested with Apple Clang)
+- Windows (tested with MSVC, MinGW)
+- Both x86 and x64 architectures
+
+### Breaking Changes
+- This is the initial release, no breaking changes apply
+
+### Security
+- All user inputs are validated and sanitized
+- No known security vulnerabilities
+- Proper bounds checking and memory safety
+- Security policy established for vulnerability reporting
+
+---
+
+## Release Notes
+
+### v0.1.0 - Initial Public Release
+
+This marks the first stable release of Argus, a modern C library for command-line argument parsing. After extensive development and testing, we're excited to offer developers a declarative, type-safe alternative to traditional argument parsing libraries.
+
+**Key Benefits:**
+- 🎯 **Type Safety**: Strong typing with automatic validation
+- 🚀 **Performance**: Fast parsing with minimal memory footprint  
+- 🛠️ **Developer Experience**: Intuitive API that reduces boilerplate
+- 📚 **Comprehensive**: Supports all common CLI patterns and more
+- 🔧 **Extensible**: Custom handlers and validators for specific needs
+
+The library is production-ready and includes comprehensive documentation, examples, and automated testing across multiple platforms.
+
+[0.1.0]: https://github.com/lucocozz/argus/releases/tag/v0.1.0
+[Unreleased]: https://github.com/lucocozz/argus/compare/v0.1.0...HEAD