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/aftersexbreakv2.json

@@ -2,36 +2,40 @@
   "action_id": "aftersexbreakv2",
   "action_name": "Aftersexbreakv2",
   "action": {
-    "full_body": "lying in bed, exhausted",
-    "head": "messy hair,  flushed face, sweating, panting",
-    "eyes": "half-closed eyes, ",
-    "arms": "",
-    "hands": "",
-    "torso": "sweaty skin, glistening skin, heavy breathing,",
-    "pelvis": "cum drip",
-    "legs": "legs spread",
-    "feet": "",
-    "additional": "ripped clothing, panties aside, rumpled bed sheets, messy bed, dim lighting, intimate atmosphere, exhausted"
-  },
-  "participants": {
-    "solo_focus": "true",
-    "orientation": "F"
+    "full_body": "lying, on_back, on_bed, bowlegged_pose, spread_legs, twisted_torso",
+    "head": "messy_hair, head_back, sweaty_face",
+    "eyes": "rolling_eyes, half-closed_eyes, ahegao",
+    "arms": "arms_spread, arms_above_head",
+    "hands": "relaxed_hands",
+    "torso": "sweat, nipples, collarbone, heavy_breathing",
+    "pelvis": "hips, navel, female_pubic_hair",
+    "legs": "spread_legs, legs_up, bent_legs",
+    "feet": "barefoot",
+    "additional": "condom_wrapper, used_tissue, stained_sheets, cum_pool, bead_of_sweat"
   },
   "lora": {
     "lora_name": "Illustrious/Poses/AfterSexBreakV2.safetensors",
     "lora_weight": 1.0,
-    "lora_triggers": "AfterSexBreakV2"
+    "lora_triggers": "aftersexbreak, after sex, male sitting"
   },
   "tags": [
-    "after sex",
-    "post-coital",
-    "lying in bed",
-    "messy hair",
-    "sweaty skin",
-    "covered by sheet",
-    "bedroom eyes",
-    "exhausted",
-    "intimate",
-    "rumpled sheets"
+    "after_sex",
+    "lying",
+    "on_back",
+    "on_bed",
+    "fucked_silly",
+    "spread_legs",
+    "bowlegged_pose",
+    "sweat",
+    "blush",
+    "messy_hair",
+    "heavy_breathing",
+    "rolling_eyes",
+    "ahegao",
+    "cum_pool",
+    "condom_wrapper",
+    "used_tissue",
+    "bed_sheet",
+    "stained_sheets"
   ]
 }