feat: implement real-time numbering preview with manual input handling

- Enhanced the `previewCode` endpoint to accept a new `manualInputValue` parameter, allowing for dynamic sequence generation based on user input.
- Updated the `NumberingRuleService` to skip legacy sequence lookups when manual input is not provided, ensuring accurate initial sequence display.
- Integrated debounce functionality in the `V2Input` component to optimize API calls for real-time suffix updates as users type.
- Refactored category resolution logic into a helper function to reduce code duplication and improve maintainability.

These changes significantly improve the user experience by providing immediate feedback on numbering sequences based on manual inputs.

backend-node/src/controllers/numberingRuleController.ts

@@ -311,13 +311,14 @@ router.post(
   async (req: AuthenticatedRequest, res: Response) => {
     const companyCode = req.user!.companyCode;
     const { ruleId } = req.params;
-    const { formData } = req.body; // 폼 데이터 (카테고리 기반 채번 시 사용)
+    const { formData, manualInputValue } = req.body;
 
     try {
       const previewCode = await numberingRuleService.previewCode(
         ruleId,
         companyCode,
-        formData
+        formData,
+        manualInputValue
       );
       return res.json({ success: true, data: { generatedCode: previewCode } });
     } catch (error: any) {