iter(g199): 新增主按钮内高光与卡片边框减负

tokens 增补：--ua-color-highlight（暗色降到 8%，暗底白高光刺眼）、
--ua-shadow-highlight（1px 内高光走令牌，皮肤不出现阴影字面值）、
--ua-tracking-wide / --ua-tracking-tight 两档字距。
主按钮叠内高光 + 悬停主题色投影，press 保留内高光；
卡片补贴地 1 档阴影，hoverable 悬停升到 2 档并同步减淡边框；
表头、选项分组标题、命令面板大写小标题统一 0.04em，
ui.css 三处字距字面值全部归零。
幽灵按钮无实色底，显式退出质感层避免透明底露白线。

Refs: g199

packages/design/tokens/tokens.json

@@ -21,6 +21,10 @@
       "light": "rgba(0, 0, 0, 0.15)",
       "dark": "rgba(255, 255, 255, 0.15)"
     },
+    "highlight": {
+      "light": "rgba(255, 255, 255, 0.5)",
+      "dark": "rgba(255, 255, 255, 0.08)"
+    },
     "accent": {
       "light": "#185fa5",
       "dark": "#378add"
@@ -78,6 +82,10 @@
     "semibold": 600,
     "bold": 700
   },
+  "tracking": {
+    "wide": "0.04em",
+    "tight": "-0.01em"
+  },
   "leading": {
     "tight": 1.35,
     "normal": 1.55,
@@ -111,6 +119,10 @@
       "light": "0 8px 20px color-mix(in srgb, var(--ua-color-accent) 35%, transparent)",
       "dark": "0 8px 20px color-mix(in srgb, var(--ua-color-accent) 40%, transparent)"
     },
+    "highlight": {
+      "light": "inset 0 1px 0 var(--ua-color-highlight)",
+      "dark": "inset 0 1px 0 var(--ua-color-highlight)"
+    },
     "hairline": {
       "light": "inset 0 -1px 0 var(--ua-border-subtle)",
       "dark": "inset 0 -1px 0 var(--ua-border-subtle)"
@@ -137,10 +149,12 @@
       "loopFast": "0.6s",
       "loopMid": "0.8s",
       "loopSlow": "1.2s",
-      "loopLong": "1.6s"
+      "loopLong": "1.6s",
+      "step": "0.02s"
     },
     "ease": "cubic-bezier(0.2, 0.8, 0.2, 1)",
-    "easeOut": "cubic-bezier(0.16, 1, 0.3, 1)"
+    "easeOut": "cubic-bezier(0.16, 1, 0.3, 1)",
+    "easeSpring": "cubic-bezier(0.34, 1.3, 0.5, 1)"
   },
   "focus": {
     "ring": {