ui(deploy): router blocker + DS dialog for unsaved edits

- Add deployedConfigSnapshot field to Deployment interface (mirrors server shape)
- Remove the Task 10.3 cast in handleRestore now that the type has the field
- New useUnsavedChangesBlocker hook (react-router useBlocker, v7.13.1)
- Wire AlertDialog into AppDeploymentPage for in-app navigation guard

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ui/src/pages/AppsTab/AppDeploymentPage/hooks/useUnsavedChangesBlocker.ts

@@ -0,0 +1,26 @@
+import { useState, useEffect } from 'react';
+import { useBlocker } from 'react-router';
+
+export function useUnsavedChangesBlocker(hasUnsavedChanges: boolean) {
+  const blocker = useBlocker(({ currentLocation, nextLocation }) =>
+    hasUnsavedChanges && currentLocation.pathname !== nextLocation.pathname
+  );
+
+  const [dialogOpen, setDialogOpen] = useState(false);
+
+  useEffect(() => {
+    if (blocker.state === 'blocked') setDialogOpen(true);
+  }, [blocker.state]);
+
+  return {
+    dialogOpen,
+    confirm: () => {
+      setDialogOpen(false);
+      blocker.proceed?.();
+    },
+    cancel: () => {
+      setDialogOpen(false);
+      blocker.reset?.();
+    },
+  };
+}