优化: 溢出修复与视觉token收敛+三处小清理

- diff长行折行可读/任务描述与产出宽表格横滚/确认弹窗长路径折行
- 滚动条色抽token浅色主题可见/阶段徽章与优先级色对齐语义token
- git状态色与错误色替换散落硬编码
- alert残留换toast走i18n/分离窗口缺参数补错误态/dev路由生产守卫

src/styles/global.css

@@ -49,6 +49,10 @@
   --df-border:            rgba(255,255,255,0.06);
   --df-border-strong:     rgba(255,255,255,0.10);
 
+  /* — Scrollbar: 滚动条 thumb(默认深色值,浅色主题在 [data-theme="light"] 覆写)— */
+  --df-scrollbar:         rgba(255,255,255,0.08);
+  --df-scrollbar-hover:   rgba(255,255,255,0.14);
+
   /* — Radius: 2/4/6/8/10 渐进（全站统一走 token）— */
   --df-radius-xs:         2px;
   --df-radius-sm:         4px;
@@ -107,6 +111,9 @@
 
   --df-border:            rgba(0,0,0,0.08);
   --df-border-strong:     rgba(0,0,0,0.14);
+
+  --df-scrollbar:         rgba(0,0,0,0.2);
+  --df-scrollbar-hover:   rgba(0,0,0,0.3);
 }
 
 * { margin: 0; padding: 0; box-sizing: border-box; }
@@ -129,8 +136,8 @@ html, body, #app {
 /* — Scrollbar — */
 ::-webkit-scrollbar { width: 5px; height: 5px; }
 ::-webkit-scrollbar-track { background: transparent; }
-::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.08); border-radius: var(--df-radius-xs); }
-::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,0.14); }
+::-webkit-scrollbar-thumb { background: var(--df-scrollbar); border-radius: var(--df-radius-xs); }
+::-webkit-scrollbar-thumb:hover { background: var(--df-scrollbar-hover); }
 
 /* — Selection — */
 /* 选中态用 accent 实色 + 白字：保证紫底气泡(accent)选中也高对比可读,