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/afteroral.json

@@ -2,33 +2,32 @@
   "action_id": "afteroral",
   "action_name": "Afteroral",
   "action": {
-    "full_body": "",
-    "head": "cum in mouth, facial, blush, open mouth, tongue out, messy hair, sweat, panting",
-    "eyes": "half-closed eyes, glazed eyes, looking up, tears",
-    "arms": "",
-    "hands": "",
-    "torso": "",
-    "pelvis": "",
-    "legs": "",
-    "feet": "",
-    "additional": "saliva, saliva string, heavy breathing, after fellatio, bodily fluids"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "Character depicted immediately after performing oral sex, often focusing on the upper body and face.",
+    "head": "Messy hair, flushed cheeks, mouth slightly open or panting.",
+    "eyes": "Half-closed or dazed expression, potentially with runny mascara or makeup.",
+    "arms": "Relaxed or wiping mouth.",
+    "hands": "Resting or near face.",
+    "torso": "Heaving chest indicative of heavy breathing.",
+    "pelvis": "N/A (typically upper body focus)",
+    "legs": "N/A",
+    "feet": "N/A",
+    "additional": "Presence of bodily fluids like saliva trails or excessive cum on face and messy makeup."
   },
   "lora": {
     "lora_name": "Illustrious/Poses/afteroral.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "afteroral"
+    "lora_triggers": "after oral, after deepthroat"
   },
   "tags": [
-    "after oral",
-    "wiping mouth",
-    "saliva",
-    "kneeling",
-    "blush",
-    "messy",
-    "panting"
+    "after_fellatio",
+    "runny_makeup",
+    "smeared_lipstick",
+    "saliva_trail",
+    "excessive_cum",
+    "messy_hair",
+    "heavy_breathing",
+    "cum_bubble",
+    "penis_on_face",
+    "sweat"
   ]
 }