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/buttercup_ppg.json

@@ -0,0 +1,58 @@
+{
+  "character_id": "buttercup_ppg",
+  "character_name": "Buttercup",
+  "identity": {
+    "base_specs": "1girl, buttercup_(ppg), aged_up, tomboy",
+    "hair": "black_hair, short_hair, bob_cut, flipped_hair",
+    "eyes": "green_eyes",
+    "hands": "",
+    "arms": "toned_arms",
+    "torso": "athletic_body, small_breasts",
+    "pelvis": "",
+    "legs": "",
+    "feet": "",
+    "extra": ""
+  },
+  "defaults": {
+    "expression": "smile, smirk",
+    "pose": "looking_at_viewer, arms_crossed",
+    "scene": ""
+  },
+  "wardrobe": {
+    "full_body": "",
+    "headwear": "",
+    "top": "green crop top, sleeveless, ",
+    "bottom": "black_belt, green shorts",
+    "legwear": "white knee high socks",
+    "footwear": "black army boots",
+    "hands": "fingerless leather gloves",
+    "accessories": ""
+  },
+  "styles": {
+    "aesthetic": "vibrant_colors, high_contrast",
+    "primary_color": "green",
+    "secondary_color": "black",
+    "tertiary_color": "white"
+  },
+  "lora": {
+    "lora_name": "",
+    "lora_weight": 1.0,
+    "lora_weight_min": 0.7,
+    "lora_weight_max": 1.0,
+    "lora_triggers": ""
+  },
+  "tags": [
+    "1girl",
+    "buttercup_(ppg)",
+    "aged_up",
+    "tomboy",
+    "short_hair",
+    "black_hair",
+    "bob_cut",
+    "green_eyes",
+    "green_dress",
+    "black_belt",
+    "white_leggings",
+    "mary_janes"
+  ]
+}