fix: 恢复LLM_API_KEY + 添加OBSIDIAN_VAULT配置

- 修复 systemd service 中损坏的 API key
- 添加 OBSIDIAN_VAULT 环境变量
- 添加 systemd override 机制

go/static/graph.html

@@ -327,7 +327,7 @@
       event: '#f85149'
     };
     
-    const API_BASE = 'http://100.65.23.30:7821';
+    const API_BASE = window.location.origin;
     const API_KEY = 'zhiyi-dev-key-2026';
     let nodes = [], links = [];
     let simulation, svg, g, linkGroup, nodeGroup, labelGroup;