docs: update documentation and add CHANGELOG

## Documentation Updates

### README.md
- Update Kotlin version badge to 1.9.22
- Update Coroutines requirement to 1.8.0+
- Add JsonMetricsExporter to architecture diagram
- Add JSON export example in Data Export section
- Update feature description for export functionality

### CHANGELOG.md (new)
- Create comprehensive changelog following Keep a Changelog format
- Document all features in v1.0.0 release
- Include unreleased changes section for recent refactoring
- Add links for version comparison

### QUICK_START.md
- Complete rewrite to use SysMetrics library API
- Remove outdated manual file copying approach
- Add proper initialization in Application class
- Add overlay configuration examples
- Add programmatic metrics access examples
- Update troubleshooting section
- Add integration checklist

This improves developer experience with accurate, up-to-date documentation.

Author: yhtyyar

CHANGELOG.md

@@ -0,0 +1,86 @@
+# 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]
+
+### Added
+- Gradle Version Catalog (`libs.versions.toml`) for centralized dependency management
+- `HealthIssue.getRecommendations()` method for individual issue recommendations
+
+### Changed
+- Centralized recommendation logic in `HealthIssue` enum (DRY principle)
+- Extracted magic numbers to named constants in `MetricsOverlayView`
+- Registered `JsonMetricsExporter` in `ExportManager` (was implemented but not registered)
+
+### Fixed
+- JSON export format now available via `SysMetrics.exportMetrics(format = "json")`
+
+## [1.0.0] - 2025-01-20
+
+### Added
+- **Core Module (`sysmetrics-core`)**
+  - `SysMetrics` singleton API for metrics collection
+  - CPU metrics: usage percentage, core count, frequencies
+  - Memory metrics: total, used, free, available, usage percentage
+  - Battery metrics: level, temperature, status, health, plugged state
+  - Thermal metrics: CPU temperature, battery temperature, throttling detection
+  - Storage metrics: total, used, free storage capacity
+  - Network metrics: RX/TX bytes, speeds, connection type, connectivity status
+  - `Flow`-based reactive streams for real-time metrics observation
+  - Health score calculation with weighted factors (CPU 30%, Memory 35%, Temperature 20%, Battery 15%)
+  - Health issue detection and recommendation generation
+  - Metrics history with configurable size (max 300 items)
+  - Time-window aggregation (1min, 5min, 30min, 1hour)
+  - CSV export (RFC 4180 compliant) with Excel compatibility
+  - JSON export for API responses and log aggregation
+  - TTL-based caching (500ms default)
+  - Configurable logging (DEBUG, INFO, WARN, ERROR levels)
+  - Thread-safe implementation with Mutex and Atomic types
+
+- **Overlay Module (`sysmetrics-overlay`)**
+  - In-app debug overlay (HUD) for real-time metrics visualization
+  - FPS monitoring via Choreographer
+  - Collapsed mode: FPS, CPU%, RAM%, Network speed
+  - Expanded mode: Full metrics including battery, thermal, storage details
+  - Draggable overlay positioning
+  - Configurable colors, opacity, text size
+  - Automatic lifecycle management
+  - Release build safety (disabled by default in release)
+
+- **Architecture**
+  - Clean Architecture with Domain/Data/Infrastructure layers
+  - Strategy Pattern for aggregation algorithms
+  - Repository Pattern for data access
+  - Dependency Injection ready design
+
+- **Documentation**
+  - Comprehensive README with Quick Start guide
+  - Full API reference
+  - Bilingual documentation (English/Russian)
+  - Overlay usage guide
+  - Architecture documentation
+
+### Technical Details
+- Min SDK: 21 (Android 5.0)
+- Target SDK: 34 (Android 14)
+- Kotlin: 1.9.22
+- Coroutines: 1.8.0
+- Kotlinx Serialization: 1.6.2
+- Explicit API mode enabled
+
+## [0.1.0] - 2025-01-15
+
+### Added
+- Initial project structure
+- Basic CPU and memory metrics collection
+- Proof of concept implementation
+
+---
+
+[Unreleased]: https://github.com/yhtyyar/sysmetrics-android/compare/v1.0.0...HEAD
+[1.0.0]: https://github.com/yhtyyar/sysmetrics-android/compare/v0.1.0...v1.0.0
+[0.1.0]: https://github.com/yhtyyar/sysmetrics-android/releases/tag/v0.1.0

README.md

@@ -2,7 +2,7 @@
 
 [![License](https://img.shields.io/badge/License-MIT-green.svg)](https://opensource.org/licenses/MIT)
 [![API](https://img.shields.io/badge/API-21%2B-brightgreen.svg)](https://android-arsenal.com/api?level=21)
-[![Kotlin](https://img.shields.io/badge/Kotlin-1.9.10-blue.svg)](https://kotlinlang.org)
+[![Kotlin](https://img.shields.io/badge/Kotlin-1.9.22-blue.svg)](https://kotlinlang.org)
 
 A production-ready Android library for collecting comprehensive system metrics including CPU, memory, battery, thermal, storage, and network information.
 
@@ -22,7 +22,7 @@ A production-ready Android library for collecting comprehensive system metrics i
 - 🔒 **Thread-safe** - Safe concurrent access
 - ⚡ **High Performance** - <5ms latency, <5MB memory
 - 🎯 **Zero Dependencies** - Only Kotlin stdlib, Coroutines, Serialization
-- 📤 **Data Export** - CSV and JSON export functionality
+- 📤 **Data Export** - CSV and JSON export with streaming support
 - 🖥️ **Debug Overlay** - In-app HUD for real-time metrics visualization (optional module)
 
 ## Installation
@@ -254,6 +254,19 @@ val europeanConfig = CsvExportConfig(
     includeHeaders = true,
     lineEnding = "\r\n"        // RFC 4180 compliant
 )
+
+// Export to JSON format
+lifecycleScope.launch {
+    val history = SysMetrics.getMetricsHistory(50).getOrNull() ?: emptyList()
+    
+    SysMetrics.exportMetrics(
+        metrics = history,
+        format = "json"  // JSON format
+    ).onSuccess { json ->
+        // Use for API responses or log aggregation
+        sendToAnalyticsServer(json)
+    }
+}
 ```
 
 ### Logging Configuration
@@ -338,7 +351,7 @@ sysmetrics-core/                    # Core metrics library (no UI dependencies)
 ├── data/
 │   ├── repository/                 # MetricsRepositoryImpl
 │   ├── aggregation/                # MetricsAggregationStrategy
-│   ├── export/                     # CsvMetricsExporter, ExportManager
+│   ├── export/                     # CsvMetricsExporter, JsonMetricsExporter, ExportManager
 │   ├── mapper/                     # Data transformers
 │   └── cache/                      # MetricsCache (500ms TTL)
 ├── infrastructure/
@@ -362,8 +375,8 @@ sysmetrics-overlay/                 # Optional debug overlay module
 
 - **Min SDK**: 21 (Android 5.0)
 - **Target SDK**: 34 (Android 14)
-- **Kotlin**: 1.9.10+
-- **Coroutines**: 1.7.3+
+- **Kotlin**: 1.9.22+
+- **Coroutines**: 1.8.0+
 
 ## License