fix: 清理未使用代码

InvestmentPlanningCenter.tsx | 移除 activeTab / setActiveTab state 和 Context
PlansPanel.tsx               | 移除 FiPlus、FiTarget，统一使用 FiFileText
 ReviewsPanel.tsx             | 移除未使用的 FiPlus 导入
investment.ts                | 移除 activeTab / setActiveTab 类型定义

src/views/Dashboard/components/CalendarPanel.tsx

@@ -258,20 +258,6 @@ export const CalendarPanel: React.FC = () => {
 
   return (
     <Box>
-      <Flex justify="flex-end" mb={4}>
-        <Button
-          size="sm"
-          colorScheme="purple"
-          leftIcon={<FiPlus />}
-          onClick={() => {
-            if (!selectedDate) setSelectedDate(dayjs());
-            onAddOpen();
-          }}
-        >
-          添加计划
-        </Button>
-      </Flex>
-
       {loading ? (
         <Center h="560px">
           <Spinner size="xl" color="purple.500" />