chore: update changelog and add release notes for v1.3.0

Author: dmtrshat

CHANGELOG.md

@@ -1,5 +1,22 @@
 # Changelog
 
+## [v1.3.0] - 2025-02-21
+
+> Full release notes: [releases/v1.3.0.md](./releases/v1.3.0.md)
+
+### Added
+
+- **In-Memory Processing**: CSS processing without filesystem dependencies
+- **ConfigInMemory**: New configuration system for in-memory operations
+- **Enhanced Logging**: More comprehensive build progress feedback
+
+### Improved
+
+- Performance optimizations with thread-local message handling
+- Configuration management with better browserslist support
+- CLI user experience with clearer feedback
+- Code architecture with `CssBuilderBase` introduction
+
 ## [v1.2.0] - 2024-12-23
 
 > Full release notes: [releases/v1.2.0.md](./releases/v1.2.0.md)

releases/v1.3.0.md

@@ -0,0 +1,51 @@
+# v1.3.0 Liminal: Beyond the Threshold
+
+Grimoire CSS breaks free from filesystem constraints with the **v1.3.0 Liminal release**, introducing in-memory processing capabilities and significant performance enhancements. This transformative update enables seamless integration with serverless environments and web frameworks while delivering an improved developer experience.
+
+## Key Highlights
+
+- **In-Memory Processing**: Process CSS entirely in memory for runtime and serverless environments.
+- **Enhanced Configuration**: Flexible configuration management with improved browserslist support.
+- **Performance Boost**: Significant optimizations across CSS generation and file operations.
+- **Refined CLI Experience**: More intuitive and informative command-line interface.
+
+## Full Details
+
+### Enhancements
+
+- **In-Memory Mode**
+
+  - Introduced `ConfigInMemory` for configuring in-memory operations.
+  - Implemented `CssBuilderInMemory` for memory-based CSS processing.
+  - Added `build_in_memory` function for flexible I/O operations.
+  - Enhanced support for alternative storage solutions.
+
+- **Configuration Improvements**
+
+  - Restructured configuration with distinct `ConfigFs` and `ConfigInMemory` structures.
+  - Enhanced browserslist handling with `.browserslistrc` support.
+  - Improved configuration file organization and clarity.
+
+- **Performance Optimizations**
+
+  - Replaced global static `MESSAGE_BUFFER` with thread-local `RefCell`.
+  - Improved CSS generation efficiency.
+  - Optimized file system operations for better performance.
+
+- **CLI Experience**
+
+  - Enhanced build progress UI with clearer feedback.
+  - Improved error reporting and debugging experience.
+  - Added comprehensive logging for better visibility.
+
+### Documentation
+
+- Updated `README` with in-memory processing examples
+- Enhanced configuration documentation
+- Added serverless deployment guidelines
+
+### Architecture
+
+- Introduced `CssBuilderBase` for shared functionality
+- Modernized codebase structure
+- Improved code maintainability