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/goblin_molestation_illustrious.json

@@ -0,0 +1,33 @@
+{
+  "action_id": "goblin_molestation_illustrious",
+  "action_name": "Goblin Molestation Illustrious",
+  "action": {
+    "full_body": "1girl surrounded by multiple small goblins in a gangbang scenario",
+    "head": "flustered, ahegao, or distressed expression",
+    "eyes": "tearing, rolling back, or heart-shaped pupils",
+    "arms": "restrained, held back, or grabbing sheets",
+    "hands": "clenched or grasped by goblins",
+    "torso": "exposed, pinned down, size difference emphasized",
+    "pelvis": "engaged in sexual activity, hips lifted",
+    "legs": "m-legs, spread wide, or held up by goblins",
+    "feet": "toes curled in pleasure or pain",
+    "additional": "size difference, bodily fluids, messy environment, cave background"
+  },
+  "lora": {
+    "lora_name": "Illustrious/Poses/Goblin_Molestation_Illustrious.safetensors",
+    "lora_weight": 0.8,
+    "lora_triggers": "Goblinestation, gangbang, many goblins, multiple boys, 1girl, sex"
+  },
+  "tags": [
+    "1girl",
+    "goblin",
+    "multiple_boys",
+    "gangbang",
+    "group_sex",
+    "sex",
+    "cum",
+    "size_difference",
+    "surrounded",
+    "rape"
+  ]
+}