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/saliva_swap_illustrious.json

@@ -2,36 +2,34 @@
   "action_id": "saliva_swap_illustrious",
   "action_name": "Saliva Swap Illustrious",
   "action": {
-    "full_body": "close-up or medium shot of two characters engaged in a passionate french kiss",
-    "head": "heads tilted, faces pressing together, cheeks flushed with heavy blush",
-    "eyes": "eyes closed, shut tight, or half-closed with hearts in eyes indicating pleasure",
-    "arms": "wrapping around the partner's neck or waist, embracing tightly",
-    "hands": "cupping cheeks, holding the back of the head, or grabbing shoulders",
-    "torso": "chests pressed intimately against one another",
-    "pelvis": "hips close together",
-    "legs": "standing close or intertwined if sitting",
-    "feet": "neutral or tip-toes",
-    "additional": "thick saliva trail connecting mouths, tongues touching, open mouths, exchange of fluids, messy kiss"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "close-up, upper_body",
+    "head": "profile, open_mouth, tongue_out, touching_tongues",
+    "eyes": "closed_eyes, blush",
+    "arms": "embracing, around_neck",
+    "hands": "cupping_face, gripping",
+    "torso": "upper_body",
+    "pelvis": "n/a",
+    "legs": "n/a",
+    "feet": "n/a",
+    "additional": "saliva, saliva_trail, drooling, spitting, heavy_breathing"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/saliva_swap_illustrious.safetensors",
-    "lora_weight": 1.0,
-    "lora_triggers": "saliva_swap_illustrious"
+    "lora_weight": 0.8,
+    "lora_triggers": "slvswp, saliva_swap"
   },
   "tags": [
-    "kissing",
-    "french kiss",
+    "saliva_swap",
+    "drooling",
     "saliva",
-    "saliva trail",
+    "french_kiss",
+    "open_mouth",
     "tongue",
-    "open mouth",
-    "duo",
-    "romantic",
-    "intimate",
-    "blush"
+    "tongue_out",
+    "saliva_trail",
+    "spitting",
+    "from_side",
+    "profile",
+    "after_kiss"
   ]
 }