Persist results to sessionStorage on all pages - prevents data loss on external link clicks

frontend/src/pages/PlaylistGenerator.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react'
+import { useState, useEffect } from 'react'
 import { ListMusic, Loader2, Save, Copy, Check, ExternalLink } from 'lucide-react'
 import { generatePlaylist, type GeneratedPlaylistResponse } from '../lib/api'
 
@@ -9,11 +9,22 @@ export default function PlaylistGenerator() {
   const [count, setCount] = useState(25)
   const [loading, setLoading] = useState(false)
   const [error, setError] = useState('')
-  const [result, setResult] = useState<GeneratedPlaylistResponse | null>(null)
+  const [result, setResult] = useState<GeneratedPlaylistResponse | null>(() => {
+    try {
+      const saved = sessionStorage.getItem('vynl_playlist_gen_results')
+      return saved ? JSON.parse(saved) : null
+    } catch { return null }
+  })
   const [saving, setSaving] = useState(false)
   const [saved, setSaved] = useState(false)
   const [copied, setCopied] = useState(false)
 
+  useEffect(() => {
+    if (result) {
+      sessionStorage.setItem('vynl_playlist_gen_results', JSON.stringify(result))
+    }
+  }, [result])
+
   const handleGenerate = async () => {
     if (!theme.trim()) return
     setLoading(true)