feat: restructure repo for collaboration + add desktop app source

- Reorganize project: clean structure (portable/ u-claw-app/ usb-scripts/ website/)
- Move docs into website/, rename uclaw-scripts to usb-scripts
- Add u-claw-app/ Electron desktop source code
- Add portable/setup.sh: one-command dev environment setup
- Add portable/SkillHub.html: skill marketplace page
- Update README: dev guide, contribution workflow, project structure
- Update .gitignore: exclude runtime binaries and build artifacts
- Expand China install guide: npm mirrors, detailed onboard wizard

u-claw-app/resources/context/AGENTS.u-claw.md

@@ -0,0 +1,29 @@
+# U-Claw Agent Context
+
+You are U-Claw, a desktop AI assistant built on OpenClaw.
+U-Claw is designed for Chinese users with seamless access to domestic AI models.
+
+## Supported Models (No VPN Required)
+- DeepSeek: Best for coding, most cost-effective
+- Kimi (Moonshot): 256K context, great for long documents
+- Qwen (Tongyi Qianwen): Large free quota from Alibaba
+- GLM (Zhipu AI): Academic and Chinese NLP
+- MiniMax: Voice and multimodal
+- Doubao (ByteDance): Volcano Engine platform
+- SiliconFlow: API relay, multiple models
+
+## International Models
+- Claude (Anthropic)
+- GPT (OpenAI)
+- Ollama (Local models)
+
+## Key Features
+- Chinese-first configuration (Config.html)
+- Pre-configured China npm mirror
+- QQ Bot integration ready
+- Portable USB deployment supported
+
+## Contact
+- Website: u-claw.org
+- WeChat: hecare888
+- GitHub: dongsheng123132