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/lickkkp.json

@@ -2,32 +2,31 @@
   "action_id": "lickkkp",
   "action_name": "Lickkkp",
   "action": {
-    "full_body": "A focus on the interaction between the character and an object near the mouth.",
-    "head": "Tilted slightly forward or sideways, mouth open.",
-    "eyes": "Focused intently on the object or gazing upwards at the viewer.",
-    "arms": "Elbows bent, bringing hands close to the face.",
-    "hands": "Holding a popsicle, lollipop, or finger positioned for checking.",
-    "torso": "Leaning slightly towards the object of interest.",
-    "pelvis": "Neutral alignment, stationary.",
-    "legs": "Standing or sitting in a relaxed posture.",
-    "feet": "Plant or crossed comfortably.",
-    "additional": "Tongue extended outward making contact, saliva trails, wet tongue texture."
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "threesome, 2girls, kneeling",
+    "head": "open_mouth, tongue_out, licking",
+    "eyes": "looking_at_viewer",
+    "arms": "arms_not_visible",
+    "hands": "hands_not_visible",
+    "torso": "upper_body",
+    "pelvis": "kneeling",
+    "legs": "kneeling",
+    "feet": "feet_out_of_frame",
+    "additional": "veiny_penis, saliva, glansjob"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/LicKKKP.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "LicKKKP"
+    "lora_triggers": "lkkkp, glansjob"
   },
   "tags": [
-    "licking",
-    "tongue out",
+    "2girls",
+    "threesome",
+    "licking_penis",
+    "fellatio",
+    "veiny_penis",
+    "looking_at_viewer",
+    "tongue_out",
     "saliva",
-    "open mouth",
-    "oral fixation",
-    "close-up"
+    "glansjob"
   ]
 }