feat: add AG-UI-4K Kotlin Multiplatform SDK

Introduces a comprehensive Kotlin Multiplatform SDK for the Agent User Interaction Protocol (AG-UI) supporting Android, iOS, and JVM platforms.

## Features
- Modular architecture with 4 specialized modules (core, client, tools, agent-sdk)
- Real-time streaming with SSE support
- Type-safe protocol implementation with kotlinx.serialization
- Extensible tool execution framework
- State management with JSON Patch support
- Multiple authentication methods (Bearer, API Key, Basic Auth)

## Modules
- **kotlin-core**: Protocol types, events, and message definitions
- **kotlin-client**: HTTP transport, SSE parsing, and state management
- **kotlin-tools**: Tool execution framework with error handling
- **kotlin-agent-sdk**: High-level agent implementations

## Examples
- Chat application with Compose Multiplatform UI
- Java Android chat app demonstrating interop
- Tool executor examples

## Testing
- 140+ unit tests across all modules
- Platform-specific test coverage
- Integration test suites

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: contextablemark

kotlin-sdk/.gitignore

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+# IDE and build files
+.idea/
+*.iml
+*.ipr
+*.iws
+.vscode/
+.fleet/
+
+# Gradle
+.gradle/
+build/
+gradle-app.setting
+!gradle-wrapper.jar
+.gradletasknamecache
+
+# Local configuration
+local.properties
+*.local
+
+# OS-specific files
+.DS_Store
+Thumbs.db
+*.swp
+*.swo
+*~
+
+# Android
+*.apk
+*.ap_
+*.aab
+*.dex
+*.class
+captures/
+.externalNativeBuild
+.cxx
+
+# iOS
+*.mode1v3
+*.mode2v3
+*.moved-aside
+*.pbxuser
+*.perspectivev3
+**/*.xcworkspace/xcuserdata/
+**/*.xcodeproj/xcuserdata/
+*.xccheckout
+*.xcscmblueprint
+DerivedData/
+*.hmap
+*.ipa
+*.dSYM.zip
+*.dSYM
+
+# Kotlin
+*.kotlin_module
+.kotlin/
+
+# Logs
+*.log
+logs/
+
+# Testing
+*.exec
+*.ec
+test-results/
+reports/
+
+# Claude-specific files
+CLAUDE.md
+claude.json
+.claude/
+
+# Documentation build output
+docs/api/
+dokka/
+
+# Maven/Publishing
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+
+# JVM crash logs
+hs_err_pid*
+
+# Temporary files
+tmp/
+temp/
+*.tmp
+*.bak
+*.backup
+
+# Package files
+*.jar
+!gradle/wrapper/gradle-wrapper.jar
+*.war
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# Virtual machine crash logs
+hs_err_pid*

kotlin-sdk/CHANGELOG.md

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+### Performance Improvements
+- Up to 2x faster compilation with K2 compiler
+- Reduced memory usage in streaming scenarios
+- Smaller binary sizes due to better optimization
+- Improved coroutine performance with latest kotlinx.coroutines# Changelog
+
+All notable changes to ag-ui-4k 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).
+
+## [0.1.0] - 2025-06-14
+
+### Added
+- Initial release of ag-ui-4k client library
+- Core AG-UI protocol implementation for Kotlin Multiplatform
+- HttpAgent client with SSE support for connecting to AG-UI agents
+- Event-driven streaming architecture using Kotlin Flows
+- Full type safety with sealed classes for events and messages
+- Support for Android, iOS, and JVM platforms
+- Comprehensive event types (lifecycle, messages, tools, state)
+- State management with snapshots and deltas
+- Tool integration for human-in-the-loop workflows
+- Cancellation support through coroutines
+- Built with Kotlin 2.1.21 and K2 compiler
+- Powered by Ktor 3.1.3 for networking
+- Uses kotlinx.serialization 1.8.1 for JSON handling
+- Comprehensive documentation and examples
+- GitHub Actions CI/CD workflow
+- Detekt static code analysis

kotlin-sdk/LICENSE

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+MIT License
+
+Copyright (c) 2025 Mark Fogle
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.