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/looks/bubblegum_ill.json

@@ -1,7 +1,7 @@
 {
   "look_id": "bubblegum_ill",
   "look_name": "Bubblegum Ill",
-  "character_id": "",
+  "character_id": "princess_bubblegum",
   "positive": "princess_bonnibel_bubblegum, adventure_time, 1girl, pink_skin, pink_hair, long_hair, pink_dress, puffy_short_sleeves, long_skirt, crown, no_nose",
   "negative": "nose, realistic, photorealistic, 3d, human",
   "lora": {
@@ -20,4 +20,4 @@
     "pink_dress",
     "crown"
   ]
-}
+}