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/views/Tasks.vue

@@ -825,7 +825,7 @@ function openCreateModal(parent?: TaskRecord) {
 }
 
 async function confirmCreate() {
-  if (!newTaskProjectId.value) { alert('请选择项目'); return }
+  if (!newTaskProjectId.value) { showToast(t('tasks.err.selectProject'), 'error'); return }
   if (!newTaskTitle.value.trim()) return
   submitting.value = true
   try {
@@ -1244,7 +1244,7 @@ onUnmounted(() => {
   flex-shrink: 0;
 }
 .priority-critical { background: rgba(255,107,107,0.2); color: var(--df-danger); }
-.priority-high { background: rgba(255,152,0,0.2); color: #ff9800; }
+.priority-high { background: rgba(255,152,0,0.2); color: var(--df-warning); }
 .priority-medium { background: rgba(100,181,246,0.2); color: var(--df-info); }
 .priority-low { background: rgba(90,99,128,0.2); color: var(--df-text-dim); }