Add Checkpoints Gallery with per-checkpoint generation settings

- New Checkpoint model (slug, name, checkpoint_path, data JSON, image_path)
- sync_checkpoints() loads metadata from data/checkpoints/*.json and falls
  back to template defaults for models without a JSON file
- _apply_checkpoint_settings() applies per-checkpoint steps, CFG, sampler,
  base positive/negative prompts, and VAE (with dynamic VAELoader node
  injection for non-integrated VAEs) to the ComfyUI workflow
- Bulk Create from Checkpoints: scans Illustrious/Noob model directories,
  reads matching HTML files, uses LLM to populate metadata, falls back to
  template defaults when no HTML is present
- Gallery index with batch cover generation and WebSocket progress bar
- Detail page showing Generation Settings and Base Prompts cards
- Checkpoints nav link added to layout
- New data/prompts/checkpoint_system.txt LLM system prompt
- Updated README with all current galleries and file structure
- Also includes accumulated action/scene JSON updates, new actions, and
  other template/generator improvements from prior sessions

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

data/actions/gyaru_v_illustriousxl_lora_nochekaiser.json

@@ -2,34 +2,32 @@
   "action_id": "gyaru_v_illustriousxl_lora_nochekaiser",
   "action_name": "Gyaru V Illustriousxl Lora Nochekaiser",
   "action": {
-    "full_body": "medium shot of a character performing the viral gyaru peace gesture, leaning slightly forward towards the viewer",
-    "head": "tilted slightly to the side with a confident or playful expression",
-    "eyes": "looking at viewer, winking or wide open",
-    "arms": "elbow bent, forearm raised and wrist rotated",
-    "hands": "inverted v-sign, peace sign fingers pointing down, palm facing inwards towards the body (gyaru peace)",
-    "torso": "upper body angled towards the camera",
-    "pelvis": "hips slightly cocked to the side",
-    "legs": "standing pose, weight on one leg",
-    "feet": "default standing position",
-    "additional": "focus on the specific inverted hand gesture characteristic of the 2020s gyaru trend"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "leaning_forward, standing or cowboy_shot",
+    "head": "tilted_head, smile, blush, open_mouth or grin",
+    "eyes": "one_eye_closed, glowing_eyes or winking, looking_at_viewer",
+    "arms": "arm_up, reaching_towards_viewer",
+    "hands": "v_over_eye, v_sign, fingers_near_face",
+    "torso": "leaning_forward, upper_body",
+    "pelvis": "n/a",
+    "legs": "n/a",
+    "feet": "n/a",
+    "additional": "selfie, gyaru, energetic atmosphere"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/gyaru-v-illustriousxl-lora-nochekaiser.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "gyaru-v-illustriousxl-lora-nochekaiser"
+    "lora_triggers": "gyaruv"
   },
   "tags": [
-    "gyaru peace",
-    "inverted v-sign",
-    "peace sign",
-    "hand gesture",
-    "fingers pointing down",
-    "leaning forward",
-    "upper body",
-    "looking at viewer"
+    "gyaru",
+    "v_over_eye",
+    "leaning_forward",
+    "one_eye_closed",
+    "looking_at_viewer",
+    "blush",
+    "smile",
+    "selfie",
+    "open_mouth",
+    "grin"
   ]
 }