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/cuminhands.json

@@ -2,35 +2,30 @@
   "action_id": "cuminhands",
   "action_name": "Cuminhands",
   "action": {
-    "full_body": "upper body focus, character presenting cupped hands towards the viewer",
-    "head": "looking down at hands or looking at viewer, expression of embarrassment or lewd satisfaction, blushing",
-    "eyes": "half-closed or wide open, focused on the hands",
-    "arms": "elbows bent, forearms brought together in front of the chest or stomach",
-    "hands": "cupped hands, palms facing up, fingers tight together, holding white liquid, messy hands",
-    "torso": "posture slightly hunched or leaning forward to show hands",
-    "pelvis": "stationary",
-    "legs": "kneeling or standing",
-    "feet": "planted",
-    "additional": "white liquid, seminal fluid, dripping between fingers, sticky texture, high contrast fluids"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "after_fellatio",
+    "head": "facial, cum_string, cum_in_mouth",
+    "eyes": "looking_at_hands",
+    "arms": "arms_bent",
+    "hands": "cupping_hands, cum_on_hands",
+    "torso": "upper_body",
+    "pelvis": "n/a",
+    "legs": "n/a",
+    "feet": "n/a",
+    "additional": "excessive_cum"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/cuminhands.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "cuminhands"
+    "lora_triggers": "cum on hands, cupping hands, excessive cum, cum on face, cum in mouth, cum string"
   },
   "tags": [
-    "cum in hands",
-    "cupped hands",
-    "holding cum",
-    "cum",
-    "bodily fluids",
-    "messy",
-    "palms up",
-    "sticky",
-    "white liquid"
+    "cum_on_hands",
+    "cupping_hands",
+    "excessive_cum",
+    "facial",
+    "cum_in_mouth",
+    "cum_string",
+    "after_fellatio",
+    "looking_at_hands"
   ]
 }