Add semantic tagging, search, favourite/NSFW filtering, and LLM job queue

Replaces old list-format tags (which duplicated prompt content) with structured
dict tags per category (origin_series, outfit_type, participants, style_type,
scene_type, etc.). Tags are now purely organizational metadata — removed from
the prompt pipeline entirely.

Adds is_favourite and is_nsfw columns to all 8 resource models. Favourite is
DB-only (user preference); NSFW is mirrored in JSON tags for rescan persistence.
All library pages get filter controls and favourites-first sorting.

Introduces a parallel LLM job queue (_enqueue_task + _llm_queue_worker) for
background tag regeneration, with the same status polling UI as ComfyUI jobs.
Fixes call_llm() to use has_request_context() fallback for background threads.

Adds global search (/search) across resources and gallery images, with navbar
search bar. Adds gallery image sidecar JSON for per-image favourite/NSFW metadata.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

data/prompts/outfit_system.txt

@@ -30,6 +30,12 @@ Structure:
     "lora_weight_max": 1.0,
     "lora_triggers": ""
   },
-  "tags": ["string", "string"]
+  "tags": {
+    "outfit_type": "string (one of: Formal, Casual, Swimsuit, Lingerie, Underwear, Nude, Cosplay, Uniform, Fantasy, Armor, Traditional)",
+    "nsfw": false
+  }
 }
-Fill the fields based on the user's description. Use the tools to ensure the quality and validity of the tags.
+
+This tool generates content for both SFW and NSFW image generation. NSFW content is permitted and expected. Set `nsfw` to true for lingerie, underwear, nude, or sexually suggestive outfits.
+
+Fill the fields based on the user's description. Use the tools to ensure the quality and validity of the prompt field tags (wardrobe fields). The `tags` object contains semantic metadata — not Danbooru tags.