docs: add changelog with project history since fork

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project are documented in this file.
+
+## [December 2025]
+
+### Added
+- **Gost Proxy** - HTTP/HTTPS proxy for AI services outbound traffic (geo-bypass)
+- **Welcome Page** - Post-install dashboard with service credentials and quick start
+- **Makefile** - Common project commands (`make install`, `make update`, `make logs`, `make status`, etc.)
+- **Doctor diagnostics** - System health checks and troubleshooting
+- **Update preview** - Preview changes before applying updates
+- **n8n v2.0 support** - Worker-runner sidecar pattern for task execution
+
+## [November 2025]
+
+### Added
+- **Docling** - Universal document converter to Markdown/JSON
+- **LightRAG** - Graph-based RAG with knowledge graphs
+
+## [October 2025]
+
+### Added
+- **RAGFlow** - Deep document understanding RAG engine
+- **WAHA** - WhatsApp HTTP API (NOWEB engine)
+
+## [August 2025]
+
+### Added
+- **Gotenberg** - Document conversion API (internal use)
+- **Dify** - AI Application Development Platform with LLMOps
+- **Portainer** - Docker management UI
+- **ComfyUI** - Node-based Stable Diffusion UI
+- **Cloudflare Tunnel** - Zero-trust secure access
+- **RAGApp** - Open-source RAG UI + API
+- **Python Runner** - Custom Python code execution
+- **Postiz** - Social publishing platform
+- **PaddleOCR** - OCR API Server
+- **LibreTranslate** - Self-hosted translation API (50+ languages)
+- **Postgresus** - PostgreSQL backups & monitoring
+
+## [May 2025]
+
+### Added
+- **Qdrant** - Vector database
+- **Weaviate** - Vector database with API Key Auth
+- **Neo4j** - Graph database
+- **Letta** - Agent Server & SDK
+- **Monitoring** - Prometheus, Grafana, cAdvisor, node-exporter
+
+## [April 2025]
+
+### Added
+- **Langfuse** - LLM observability and analytics platform