feat: 投资日历自选股功能优化 - Redux 集成 + 乐观更新

- InvestmentCalendar: 集成 Redux 管理自选股状态
- InvestmentCalendar: 添加 isStockInWatchlist 检查，防止重复添加
- InvestmentCalendar: 按钮状态实时切换（加自选/已关注）
- stockSlice: 实现乐观更新，pending 时立即更新 UI
- stockSlice: rejected 时自动回滚状态并提示错误
- 移除不必要的 loading 状态，提升用户体验

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/store/slices/stockSlice.js

@@ -440,9 +440,10 @@ const stockSlice = createSlice({
         state.loading.allStocks = false;
       })
 
-      // ===== toggleWatchlist =====
-      .addCase(toggleWatchlist.fulfilled, (state, action) => {
-        const { stockCode, stockName, isInWatchlist } = action.payload;
+      // ===== toggleWatchlist（乐观更新）=====
+      // pending: 立即更新状态
+      .addCase(toggleWatchlist.pending, (state, action) => {
+        const { stockCode, stockName, isInWatchlist } = action.meta.arg;
         if (isInWatchlist) {
           // 移除
           state.watchlist = state.watchlist.filter(item => item.stock_code !== stockCode);
@@ -453,6 +454,25 @@ const stockSlice = createSlice({
             state.watchlist.push({ stock_code: stockCode, stock_name: stockName });
           }
         }
+      })
+      // rejected: 回滚状态
+      .addCase(toggleWatchlist.rejected, (state, action) => {
+        const { stockCode, stockName, isInWatchlist } = action.meta.arg;
+        // 回滚：与 pending 操作相反
+        if (isInWatchlist) {
+          // 之前移除了，现在加回来
+          const exists = state.watchlist.some(item => item.stock_code === stockCode);
+          if (!exists) {
+            state.watchlist.push({ stock_code: stockCode, stock_name: stockName });
+          }
+        } else {
+          // 之前添加了，现在移除
+          state.watchlist = state.watchlist.filter(item => item.stock_code !== stockCode);
+        }
+      })
+      // fulfilled: 乐观更新模式下状态已在 pending 更新，这里无需操作
+      .addCase(toggleWatchlist.fulfilled, () => {
+        // 状态已在 pending 时更新
       });
   }
 });