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/illustrious_standing_cunnilingus_000010.json

@@ -2,32 +2,31 @@
   "action_id": "illustrious_standing_cunnilingus_000010",
   "action_name": "Illustrious Standing Cunnilingus 000010",
   "action": {
-    "full_body": "duo focus, standing position, one person lifting another, standing cunnilingus, carry",
-    "head": "face buried in crotch, head between legs, ecstatic expression, tongue out",
-    "eyes": "eyes closed, rolling eyes, heart-shaped pupils",
-    "arms": "arms under buttocks, holding legs, arms wrapped around neck",
-    "hands": "squeezing butt, hands on head, fingers in hair",
-    "torso": "back arched, chest pressed",
-    "pelvis": "pussy exposed, genital contact",
-    "legs": "legs wrapped around waist, spread legs, legs over shoulders",
-    "feet": "toes curled, feet dangling",
-    "additional": "saliva, motion lines, sexual act"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "standing cunnilingus, femdom, 1girl standing, 1boy kneeling",
+    "head": "looking down, evil smirk",
+    "eyes": "looking at partner",
+    "arms": "arms at sides or arms behind head",
+    "hands": "resting on partner's head",
+    "torso": "facing viewer or facing partner",
+    "pelvis": "legs apart",
+    "legs": "standing",
+    "feet": "standing",
+    "additional": "male between legs, oral sex, forced cunnilingus"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/Illustrious_Standing_Cunnilingus-000010.safetensors",
-    "lora_weight": 1.0,
-    "lora_triggers": "Illustrious_Standing_Cunnilingus-000010"
+    "lora_weight": 0.65,
+    "lora_triggers": "PWF1, pussy worship, femdom, cunnilingus, licks pussy, standing"
   },
   "tags": [
-    "standing cunnilingus",
-    "lifting person",
-    "carry",
-    "legs around waist",
-    "oral sex",
-    "nsfw"
+    "standing_cunnilingus",
+    "cunnilingus",
+    "femdom",
+    "standing",
+    "kneeling",
+    "looking_down",
+    "legs_apart",
+    "between_legs",
+    "forced_cunnilingus"
   ]
 }