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/checkpoints/illustrious_kawaiialluxanime.json

@@ -1,11 +1,11 @@
 {
-  "checkpoint_path": "Illustrious/kawaiialluxanime_.safetensors",
-  "checkpoint_name": "kawaiialluxanime_.safetensors",
-  "base_positive": "masterpiece, best quality, absurdres, amazing quality, intricate details",
   "base_negative": "lowres, worst quality, low quality, bad anatomy, bad hand, extra digits, ",
-  "steps": 25,
-  "cfg": 5.0,
+  "base_positive": "masterpiece, best quality, absurdres, amazing quality, intricate details",
+  "cfg": 5,
+  "checkpoint_name": "kawaiialluxanime_.safetensors",
+  "checkpoint_path": "Illustrious/kawaiialluxanime_.safetensors",
+  "sampler_name": "euler_ancestral",
   "scheduler": "normal",
-  "sampler_name":  "euler_ancestral",
-  "vae": "integrated"
+  "steps": 25,
+  "vae": "sdxl_vae.safetensors"
 }