docs(design): 解压 Maestro Design System 到 design/（重构参照材料）

phosphor console v1.1 设计系统（从现网 web/style.css 演化）：tokens(colors/effects/
typography/fonts) + components(core/forms/surfaces .jsx) + ui_kits(console + console_mobile)
+ assets/icons(15 双色 SVG) + guidelines + CLAUDE/SKILL/readme。供 B1–B6 重构任务对照实现。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

design/components/forms/Textarea.jsx

@@ -0,0 +1,17 @@
+import { ensureFieldCss } from './Input.jsx';
+
+export function Textarea({ label, required, placeholder, value, defaultValue, onChange, minHeight = 72, danger, style }) {
+  ensureFieldCss();
+  const ctrl = (
+    <textarea className="m-input" placeholder={placeholder} value={value} defaultValue={defaultValue}
+      style={{ resize: 'vertical', minHeight, width: '100%', ...(danger ? { borderColor: 'var(--red-dim)' } : {}), ...style }}
+      onChange={onChange ? (e) => onChange(e.target.value) : undefined} readOnly={value !== undefined && !onChange} />
+  );
+  if (!label) return ctrl;
+  return (
+    <label className="m-label" style={{ width: '100%' }}>
+      <span>{label}{required ? <span className="m-req"> *</span> : null}</span>
+      {ctrl}
+    </label>
+  );
+}