Add extra prompts, endless generation, random character default, and small fixes

- Add extra positive/negative prompt textareas to all 9 detail pages with session persistence
- Add Endless generation button to all detail pages (continuous preview generation until stopped)
- Default character selector to "Random Character" on all secondary detail pages
- Fix queue clear endpoint (remove spurious auth check)
- Refactor app.py into routes/ and services/ modules
- Update CLAUDE.md with new architecture documentation
- Various data file updates and cleanup

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

data/styles/anime_artistic_2.json

@@ -3,7 +3,7 @@
   "style_name": "Anime Artistic 2",
   "style": {
     "artist_name": "",
-    "artistic_style": ""
+    "artistic_style": "anime, artistic, digital painting"
   },
   "lora": {
     "lora_name": "Illustrious/Styles/Anime_artistic_2.safetensors",
@@ -12,4 +12,4 @@
     "lora_weight_min": 1.0,
     "lora_weight_max": 1.0
   }
-}
+}