Update screensaver prompt generation for more variety

- Changed auto-prompt instructions to encourage diverse subjects
- Prevents defaulting to same subject type repeatedly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: G-Fourteen

apps/screensaverDemo/screensaver.js

@@ -296,7 +296,7 @@ async function fetchImageModels() {
 // ===== PROMPT GENERATION =====
 
 async function fetchDynamicPrompt() {
-    const metaPrompt = "Generate exactly one short 125-character image prompt as text only of an outlandish and psychologically thrilling image.";
+    const metaPrompt = "Generate exactly one short 125-character image prompt as text only of an outlandish and psychologically thrilling image. Vary subjects - landscapes, creatures, objects, men, women, abstract. Don't default to young females.";
     const seed = generateSeed();
 
     try {