docs(guide): rewrite CLAUDE.md with ZCLAW-first perspective

Major changes:
- Shift from "OpenFang desktop client" to "independent AI Agent desktop app"
- Add decision principle: "Is this useful for ZCLAW? Does it affect ZCLAW?"
- Simplify project structure and tech stack sections
- Replace OpenClaw vs OpenFang comparison with unified backend approach
- Consolidate troubleshooting from scattered sections into organized FAQ
- Update Hands system documentation with 8 capabilities and status
- Stream

docs/features/README.md

@@ -72,7 +72,7 @@
 
 | 文档 | 功能 | 成熟度 | 测试覆盖 |
 |------|------|--------|---------|
-| [00-openfang-integration.md](06-tauri-backend/00-openfang-integration.md) | OpenFang 集成 | L4 | 高 |
+| [00-backend-integration.md](06-tauri-backend/00-backend-integration.md) | 后端集成 | L4 | 高 |
 | [01-secure-storage.md](06-tauri-backend/01-secure-storage.md) | 安全存储 | L4 | 高 |
 | [02-local-gateway.md](06-tauri-backend/02-local-gateway.md) | 本地 Gateway | L4 | 高 |