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/charm_person_magic.json

@@ -2,33 +2,32 @@
   "action_id": "charm_person_magic",
   "action_name": "Charm Person Magic",
   "action": {
-    "full_body": "standing, casting pose, dynamic angle, upper body focused",
-    "head": "facing viewer, head tilted, alluring expression, seductive smile",
-    "eyes": "looking at viewer, glowing eyes, heart-shaped pupils, hypnotic gaze",
-    "arms": "reaching towards viewer, one arm outstretched, hand near face",
-    "hands": "open palm, casting gesture, finger snaps, beckoning motion",
-    "torso": "facing forward, slight arch",
-    "pelvis": "hips swayed, weight shifted",
-    "legs": "standing, crossed legs",
-    "feet": "out of frame",
-    "additional": "pink magic, magical aura, sparkles, heart particles, glowing hands, casting spell, enchantment, visual effects"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "casting_spell, standing, magical_presence",
+    "head": "smile, confident_expression, glowing_eyes",
+    "eyes": "looking_at_viewer, glowing_eyes",
+    "arms": "outstretched_hand, reaching_towards_viewer, arms_up",
+    "hands": "open_hand, hand_gesture",
+    "torso": "upper_body, facing_viewer",
+    "pelvis": "n/a",
+    "legs": "n/a",
+    "feet": "n/a",
+    "additional": "aura, soft_light, magic_effects, sparkling"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/charm_person_magic.safetensors",
-    "lora_weight": 1.0,
-    "lora_triggers": "charm_person_magic"
+    "lora_weight": 0.7,
+    "lora_triggers": "charm_person_(magic), cham_aura"
   },
   "tags": [
+    "casting_spell",
     "magic",
-    "fantasy",
-    "enchantment",
-    "hypnotic",
-    "alluring",
-    "spellcasting",
-    "pink energy"
+    "aura",
+    "outstretched_hand",
+    "reaching_towards_viewer",
+    "glowing_eyes",
+    "looking_at_viewer",
+    "smile",
+    "cowboy_shot",
+    "solo"
   ]
 }