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/midis_cumshower_lr_v1_naixl_vpred_.json

@@ -2,35 +2,33 @@
   "action_id": "midis_cumshower_lr_v1_naixl_vpred_",
   "action_name": "Midis Cumshower Lr V1 Naixl Vpred ",
   "action": {
-    "full_body": "kneeling or standing pose, body seemingly under a waterfall of viscous liquid",
-    "head": "tilted back, looking up, facial, face covered in white liquid, dripping heavily",
-    "eyes": "eyes closed or squinting, eyelashes wet and clumped, messy face",
-    "arms": "arms relaxed or hands touching face, skin slick with liquid",
-    "hands": "messy hands, covered in cum, spread palms",
-    "torso": "chest covered in liquid, streams running down the body, wet skin shine",
-    "pelvis": "kneeling or stationary",
-    "legs": "thighs wet, liquid pooling",
-    "feet": "bare feet",
-    "additional": "heavy cum, excessive cum, bukkake, splashing liquid, messy"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "standing, showering",
+    "head": "wet_hair, cum_on_hair",
+    "eyes": "closed_eyes",
+    "arms": "washing_hair, arms_behind_head",
+    "hands": "hands_on_head",
+    "torso": "wet, cum_on_body",
+    "pelvis": "wet",
+    "legs": "standing",
+    "feet": "barefoot",
+    "additional": "steam, bathroom, shower_head, excessive_cum"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/midis_CumShower_LR-V1[NAIXL-vPred].safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "midis_CumShower_LR-V1[NAIXL-vPred]"
+    "lora_triggers": "showering, cumshower"
   },
   "tags": [
-    "cum_shower",
-    "bukkake",
-    "heavy_cum",
-    "facial",
-    "covered_in_cum",
-    "excessive_cum",
-    "dripping_cum",
-    "messy",
-    "body_bukkake"
+    "showering",
+    "washing_hair",
+    "wet",
+    "wet_hair",
+    "steam",
+    "bathroom",
+    "cum",
+    "cum_on_body",
+    "cum_on_hair",
+    "arms_behind_head",
+    "closed_eyes"
   ]
 }