B6: SPA navigation after case creation (useNavigate instead of window.location.href)

B7: stop AdminDashboard refetching the case list on selection change

selectedCaseId was both read and written inside the list-loading effect and
listed in its deps, causing a second fetch on first render and after every
filter reset. Auto-select now uses a functional state update, so the effect
no longer depends on selectedCaseId; editForm stays in sync via the existing
selectedCase effect.

frontend/src/components/CaseForm/CaseForm.jsx

@@ -1,4 +1,5 @@
 import React, { useState } from "react";
+import { useNavigate } from "react-router-dom";
 import Step1Child from "./Step1Child";
 import Step2Health from "./Step2Health";
 import Step2bPsychotype from "./Step2bPsychotype";
@@ -16,6 +17,7 @@ const INITIAL_DATA = {
 };
 
 const CaseForm = ({ isMobile = false }) => {
+  const navigate = useNavigate();
   const [currentStep, setCurrentStep] = useState(1);
   const [formData, setFormData] = useState(INITIAL_DATA);
   const [errors, setErrors] = useState([]);
@@ -116,10 +118,11 @@ const CaseForm = ({ isMobile = false }) => {
       }
       
       const result = await response.json();
-      
-      // Перенаправляем на страницу анализа с ID карточки
-      window.location.href = `/analysis/${result.id}`;
-      
+
+      // Перенаправляем на страницу анализа с ID карточки.
+      // SPA-переход: полная перезагрузка теряла состояние приложения.
+      navigate(`/analysis/${result.id}`);
+
     } catch (err) {
       setErrors([err.message || "Ошибка при отправке данных"]);
     } finally {