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/characters/shiki_senran_kagura.json

@@ -0,0 +1,57 @@
+{
+  "character_id": "shiki_senran_kagura",
+  "character_name": "Shiki",
+  "identity": {
+    "base_specs": "1girl, shiki_(senran_kagura), large_breasts, gyaru",
+    "hair": "blonde_hair, drill_hair, long_hair",
+    "eyes": "purple_eyes",
+    "hands": "",
+    "arms": "",
+    "torso": "cleavage",
+    "pelvis": "",
+    "legs": "",
+    "feet": "",
+    "extra": ""
+  },
+  "defaults": {
+    "expression": "smile",
+    "pose": "",
+    "scene": ""
+  },
+  "wardrobe": {
+    "full_body": "black_dress, frilled_dress, gothic_lolita",
+    "headwear": "black_hat, mini_hat",
+    "top": "",
+    "bottom": "",
+    "legwear": "black_thighhighs",
+    "footwear": "black_footwear",
+    "hands": "",
+    "accessories": "cross_necklace, scythe"
+  },
+  "styles": {
+    "aesthetic": "gothic_lolita",
+    "primary_color": "black",
+    "secondary_color": "purple",
+    "tertiary_color": "gold"
+  },
+  "lora": {
+    "lora_name": "Illustrious/Looks/shiki_kagura_ill_v01.safetensors",
+    "lora_weight": 1.0,
+    "lora_weight_min": 0.7,
+    "lora_weight_max": 1.0,
+    "lora_triggers": "shiki_(senran_kagura)"
+  },
+  "tags": [
+    "shiki_(senran_kagura)",
+    "senran_kagura",
+    "blonde_hair",
+    "drill_hair",
+    "purple_eyes",
+    "large_breasts",
+    "black_dress",
+    "mini_hat",
+    "thighhighs",
+    "cross_necklace",
+    "scythe"
+  ]
+}