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/pov_mirror_fellatio_illustrious.json

@@ -2,35 +2,35 @@
   "action_id": "pov_mirror_fellatio_illustrious",
   "action_name": "Pov Mirror Fellatio Illustrious",
   "action": {
-    "full_body": "POV shot, looking into a large mirror, reflection shows a character kneeling in front of the viewer performing oral sex",
-    "head": "head angled slightly up towards the reflection, facing the mirror",
-    "eyes": "eye contact with the viewer via the mirror reflection",
-    "arms": "reaching forward to hold the viewer's hips or thighs",
-    "hands": "hands grasping the viewer or guiding the action",
-    "torso": "leaning forward, back slightly arched",
-    "pelvis": "kneeling position, hips lower than head",
-    "legs": "kneeling on the floor, knees bent",
-    "feet": "tucked under or resting on the floor",
-    "additional": "bathroom setting, mirror frame visible, viewer's body partially visible in reflection"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "MF"
+    "full_body": "kneeling or squatting in front of a mirror",
+    "head": "facing mirror, looking at viewer in reflection",
+    "eyes": "looking at viewer",
+    "arms": "reaching forward or resting on partner",
+    "hands": "hand on another's head",
+    "torso": "facing mirror",
+    "pelvis": "ass visible, facing away from viewer (towards mirror)",
+    "legs": "kneeling or squatting",
+    "feet": "toes touching ground",
+    "additional": "viewed from behind with action visible in mirror reflection"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/POV_mirror_fellatio_Illustrious.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "POV_mirror_fellatio_Illustrious"
+    "lora_triggers": "pov, mirror, fellatio, kneeling, looking_at_viewer"
   },
   "tags": [
     "pov",
     "mirror",
-    "reflection",
     "fellatio",
-    "oral sex",
     "kneeling",
-    "looking at viewer",
-    "bathroom",
-    "nsfw"
+    "looking_at_viewer",
+    "ass",
+    "faceless_male",
+    "reflection",
+    "thong",
+    "underwear",
+    "hand_on_another's_head",
+    "nude",
+    "from_behind"
   ]
 }