fix: hide lyrics and exclude from zip and descriptions for instrumental tracks

server/prompts.mjs

@@ -26,10 +26,10 @@ REQUIRED JSON STRUCTURE:
     "Title 2: direct/strong (max 4 words)",
     "Title 3: abstract/intriguing (max 4 words)"
   ],
-  "lyrics": "Full lyrics with Suno section tags [Verse], [Chorus], [Bridge], [Outro], etc. Use AABB or ABAB rhyme scheme consistently. Lines must be rhythmically singable. CRITICAL: The lyrics must NOT reference the genre, instruments, or music production. No references to pianos, guitars, beats, orchestras, or any musical elements. Write about universal human themes: emotion, nature, love, time, memory, journey, longing.",
+  "lyrics": "If instrumental, return an empty string \"\". Otherwise: Full lyrics with Suno section tags [Verse], [Chorus], [Bridge], [Outro], etc. Use AABB or ABAB rhyme scheme consistently. Lines must be rhythmically singable. CRITICAL: The lyrics must NOT reference the genre, instruments, or music production. No references to pianos, guitars, beats, orchestras, or any musical elements. Write about universal human themes: emotion, nature, love, time, memory, journey, longing.",
   "style": "Comma-separated Suno style description, max 120 words. Include: tempo with BPM range, key instruments, production style, texture, energy level, mood, vocal style (or 'instrumental, no vocals'). NEVER name any artist, band, or use 'sounds like'.",
   "negative_style": "Comma-separated list of genres, instruments, moods, and styles that should NOT appear.",
-  "youtube_description": "In the same language as the lyrics. Follow this exact structure:\\n\\n[One evocative hook sentence tied to the mood]\\n\\n[2-3 sentences describing the music, mood, and emotional experience]\\n\\n────────────────────────────\\n\\n[Full lyrics, copied exactly]\\n\\n────────────────────────────\\n\\n[Warm, genuine call to action: ask viewers to like, subscribe, and comment what the music makes them feel or imagine]\\n\\n#hashtag1 #hashtag2 ... (12-15 hashtags: mix of genre, mood, and tool tags like #SunoAI #AIMusic)",
+  "youtube_description": "In the same language as the lyrics. Follow this exact structure:\\n\\n[One evocative hook sentence tied to the mood]\\n\\n[2-3 sentences describing the music, mood, and emotional experience]\\n\\n────────────────────────────\\n\\n[Full lyrics, copied exactly. IF INSTRUMENTAL, OMIT THIS SECTION AND THE DIVIDERS COMPLETELY]\\n\\n────────────────────────────\\n\\n[Warm, genuine call to action: ask viewers to like, subscribe, and comment what the music makes them feel or imagine]\\n\\n#hashtag1 #hashtag2 ... (12-15 hashtags: mix of genre, mood, and tool tags like #SunoAI #AIMusic)",
   "video_prompts": [
     {
       "type": "Abstract",