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/kissstanding_on_one_leg_il_000014.json

@@ -2,38 +2,32 @@
   "action_id": "kissstanding_on_one_leg_il_000014",
   "action_name": "Kissstanding On One Leg Il 000014",
   "action": {
-    "full_body": "Two characters in a romantic standing embrace, usually seen clearly from the side",
-    "head": "Faces close together, lips locked in a kiss, heads tilted slightly in opposite directions",
-    "eyes": "Closed eyes signifying intimacy",
-    "arms": "One person's arms wrapped around the other's neck, the other person's arms holding the partner's waist or back",
-    "hands": "Hands clutching clothing or resting gently on the back/waist",
-    "torso": "Chests pressing against each other, leaning in",
-    "pelvis": "Hips close together, facing each other",
-    "legs": "One character stands on one leg while the other leg is bent backward at the knee (foot pop); the partner stands firmly on both legs",
-    "feet": "One foot lifted in the air behind the body, others planted on the ground",
-    "additional": "Romantic atmosphere, height difference, anime trope 'foot pop'"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "duo, standing, standing_on_one_leg, kiss, embrace",
+    "head": "closed_eyes, tilted_head, profile",
+    "eyes": "closed_eyes",
+    "arms": "arms_around_neck, arms_around_waist, hugging",
+    "hands": "placed_on_back, placed_on_shoulders",
+    "torso": "leaning_forward, chest_press",
+    "pelvis": "facing_viewer",
+    "legs": "leg_up, bent_knee, standing_on_one_leg",
+    "feet": "one_foot_raised",
+    "additional": "romantic_ambience, height_difference"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/KIssStanding-On-One-Leg-IL-000014.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "KIssStanding-On-One-Leg-IL-000014"
+    "lora_triggers": "KSOOLIL-V1.0, standing on one leg, leg up, kiss"
   },
   "tags": [
+    "duo",
     "kiss",
-    "kissing",
-    "couple",
-    "standing on one leg",
-    "one leg up",
-    "foot pop",
-    "hugging",
+    "standing",
+    "standing_on_one_leg",
+    "leg_up",
+    "bent_knee",
     "embrace",
-    "romantic",
-    "closed eyes",
-    "side view",
-    "love"
+    "arms_around_neck",
+    "arms_around_waist",
+    "closed_eyes"
   ]
 }