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/cum_in_cleavage_illustrious.json

@@ -2,38 +2,32 @@
   "action_id": "cum_in_cleavage_illustrious",
   "action_name": "Cum In Cleavage Illustrious",
   "action": {
-    "full_body": "close-up or cowboy shot focusing intensely on the upper body and chest area",
-    "head": "flushed cheeks, heavy breathing, mouth slightly open, expression of embarrassment or pleasure, saliva trail",
-    "eyes": "half-closed, heart-shaped pupils (optional), looking down at chest or shyly at viewer",
-    "arms": "arms bent brings hands to chest level",
-    "hands": "hands squeezing breasts together to deepen cleavage, or pulling clothing aside to reveal the mess",
-    "torso": "large breasts pressed together, deep cleavage filled with pooling white seminal fluid, cum dripping down skin, messy upper body",
-    "pelvis": "obscured or hips visible in background",
-    "legs": "obscured",
-    "feet": "out of frame",
-    "additional": "high viscosity liquid detail, shiny skin, wet texture, after sex atmosphere"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "passionate upper body focus, intimacy",
+    "head": "blush, mouth slightly open, expression of pleasure or service",
+    "eyes": "looking at viewer, potentially heavy lidded or heart-shaped pupils",
+    "arms": "arms bent, hands bringing breasts together",
+    "hands": "holding own breasts, squeezing or pressing breasts together",
+    "torso": "bare chest, medium to large breasts, pronounced cleavage, cum pooling in cleavage",
+    "pelvis": "not visible or seated",
+    "legs": "not visible",
+    "feet": "not visible",
+    "additional": "pool of liquid in cleavage, messy, erotic context"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/cum_in_cleavage_illustrious.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "cum_in_cleavage_illustrious"
+    "lora_triggers": "cum_in_cleavage, holding own breasts"
   },
   "tags": [
-    "cum",
-    "cum in cleavage",
-    "cum on breasts",
-    "semen",
-    "huge breasts",
-    "cleavage",
-    "messy",
-    "sticky",
+    "cum_on_breasts",
     "paizuri",
-    "sex act",
-    "illustration",
-    "nsfw"
+    "cleavage",
+    "breasts",
+    "breast_lift",
+    "plump",
+    "mature_female",
+    "short_hair",
+    "black_hair",
+    "indoors"
   ]
 }