fix: security and code quality improvements

Security fixes:
- Add file upload size limits (10MB) for customer and product imports
- Add XLSX file validation with row limits and magic byte checking
- Implement password validation (min 6 chars) in registration
- Add rate limiting for guest login (5 per IP per 15 minutes)
- Sanitize error messages to prevent information leakage
- Fix XSS vulnerability by removing unsafe v-html usage
- Enforce WhatsApp webhook signature verification
- Add SSRF protection with URL validation and IP blocking
- Fix marketing endpoints to use proper authentication

Code quality improvements:
- Create shared utility functions for UUID validation and string sanitization
- Remove duplicate UUID validation code from admin modules
- Remove dead code (pass statement in translation.py)
- Fix aliyun SDK import compatibility

backend/app/api/v1/discovery.py

@@ -32,7 +32,8 @@ async def search_leads(req: SearchRequest, db: AsyncSession = Depends(get_db)):
         result = await svc.search(req.product_description, req.target_market)
         return {"success": True, "data": result}
     except Exception as e:
-        raise HTTPException(status_code=500, detail=f"搜索失败: {str(e)}")
+        logger.error(f"Search failed: {e}")
+        raise HTTPException(status_code=500, detail="搜索失败，请稍后重试")
 
 
 @router.post("/analyze")
@@ -46,7 +47,8 @@ async def analyze_company(req: AnalyzeRequest):
         result = await svc.analyze(req.company_url, req.product_description)
         return {"success": True, "data": result}
     except Exception as e:
-        raise HTTPException(status_code=500, detail=f"分析失败: {str(e)}")
+        logger.error(f"Analysis failed: {e}")
+        raise HTTPException(status_code=500, detail="分析失败，请稍后重试")
 
 
 @router.post("/outreach")
@@ -57,7 +59,9 @@ async def generate_outreach(req: OutreachRequest):
         raise HTTPException(status_code=400, detail="请填写产品名称")
     svc = DiscoveryService()
     try:
-        result = await svc.outreach(req.company, req.product)
+        result = await svc.generate_outreach(req.company, req.product)
         return {"success": True, "data": result}
     except Exception as e:
-        raise HTTPException(status_code=500, detail=f"生成失败: {str(e)}")
+        logger.error(f"Outreach generation failed: {e}")
+        raise HTTPException(status_code=500, detail="生成失败，请稍后重试")
+