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/fff_imminent_masturbation.json

@@ -2,38 +2,32 @@
   "action_id": "fff_imminent_masturbation",
   "action_name": "Fff Imminent Masturbation",
   "action": {
-    "full_body": "lying on back, reclining mostly nude, body tense with anticipation",
-    "head": "tilted back slightly, chin up, face flushed",
-    "eyes": "half-closed, heavy-lidded, lustful gaze",
-    "arms": "reaching downwards along the body",
-    "hands": "hovering near genitals, fingers spreading, one hand grasping thigh, one hand reaching into panties or towards crotch",
-    "torso": "arched back, chest heaving",
-    "pelvis": "tilted upward, hips lifted slightly",
-    "legs": "spread wide, knees bent and falling outward (M-legs)",
-    "feet": "toes curled",
-    "additional": "sweaty skin, disheveled clothing, underwear pulled aside, messy sheets"
-  },
-  "participants": {
-    "solo_focus": "false",
-    "orientation": "FFF"
+    "full_body": "hand_on_own_crotch, trembling, legs_together, knock-kneed",
+    "head": "heavy_breathing, sweating, looking_down",
+    "eyes": "narrowed_eyes, half-closed_eyes, dilated_pupils",
+    "arms": "arms_down, hand_between_legs",
+    "hands": "hand_on_own_crotch, squeezing, rubbing_crotch",
+    "torso": "arched_back, squirming",
+    "pelvis": "hips_forward",
+    "legs": "legs_together, knock-kneed",
+    "feet": "standing",
+    "additional": "clothed_masturbation, urgency, arousal, through_clothes"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/FFF_imminent_masturbation.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "FFF_imminent_masturbation"
+    "lora_triggers": "FFF_grabbing_own_crotch, trembling, sweat, breath, imminent_masturbation"
   },
   "tags": [
-    "solo",
-    "female",
-    "imminent masturbation",
-    "hand near crotch",
-    "hand in panties",
-    "fingering",
-    "spread legs",
-    "lying",
-    "on bed",
-    "aroused",
+    "hand_on_own_crotch",
+    "heavy_breathing",
+    "trembling",
+    "sweat",
     "blush",
-    "nsfw"
+    "legs_together",
+    "clothed_masturbation",
+    "hand_between_legs",
+    "aroused",
+    "rubbing_crotch"
   ]
 }