chore: remove prototype files and unused UI assets

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/assets/styles/global.css

@@ -23,11 +23,12 @@
   --nav-muted: #7d89a5;
   --radius: 8px;
   --ease: cubic-bezier(.2, .8, .2, 1);
-  font-family: Inter, "SF Pro Display", "Segoe UI", "PingFang SC", "Microsoft YaHei", Arial, sans-serif;
+  font-family: "LXGW WenKai", Inter, "SF Pro Display", "PingFang SC", sans-serif;
 }
 
 * { box-sizing: border-box; }
 body { margin: 0; min-height: 100dvh; color: var(--text); background: var(--bg); }
+.mdi { line-height: 1; vertical-align: middle; }
 button, input, select, textarea { font: inherit; }
 button { cursor: pointer; }
 button:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible { outline: 3px solid rgba(16,185,129,.20); outline-offset: 2px; }