feat: add StabilityMatrix-style Model Manager service

New FastAPI container (port 8189) to download and manage models:
- Installed Models, Add/Download (CivitAI/HuggingFace/direct URL), Settings views
- Persistent SQLite storage for API keys and download history (./sparkyui-data)
- Downloads land in ./models, auto-sorted into ComfyUI's standard subfolders
- Default COMFYUI_HOST_PATH and SPARKYUI_DATA_PATH to the project root
- Wire docker-compose service, env defaults, gitignore, README docs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docker-compose.yml

@@ -50,20 +50,21 @@ services:
       CUDA_CACHE_MAXSIZE: "4294967296"
 
     volumes:
-      # Models from existing ComfyUI install (read-only)
-      - ${COMFYUI_HOST_PATH}/models:/opt/ComfyUI/models:ro
+      # Models from existing ComfyUI install (read-only).
+      # Defaults to the project root; the model-manager service writes here.
+      - ${COMFYUI_HOST_PATH:-.}/models:/opt/ComfyUI/models:ro
 
       # Custom nodes - comment out to use container-only (fresh) custom_nodes
       # If mounted, ComfyUI-Manager installs persist across container restarts
-      - ${SPARKYUI_DATA_PATH}/custom_nodes:/opt/ComfyUI/custom_nodes
+      - ${SPARKYUI_DATA_PATH:-.}/custom_nodes:/opt/ComfyUI/custom_nodes
 
       # Outputs/inputs/workflows - persistent across restarts
-      - ${SPARKYUI_DATA_PATH}/output:/opt/ComfyUI/output
-      - ${SPARKYUI_DATA_PATH}/input:/opt/ComfyUI/input
-      - ${SPARKYUI_DATA_PATH}/workflows:/opt/ComfyUI/workflows
+      - ${SPARKYUI_DATA_PATH:-.}/output:/opt/ComfyUI/output
+      - ${SPARKYUI_DATA_PATH:-.}/input:/opt/ComfyUI/input
+      - ${SPARKYUI_DATA_PATH:-.}/workflows:/opt/ComfyUI/workflows
 
       # Wheel cache (optional - for prebuilt wheels)
-      - ${SPARKYUI_DATA_PATH}/wheels:/opt/wheels
+      - ${SPARKYUI_DATA_PATH:-.}/wheels:/opt/wheels
 
       # Sparky patches - Grace-Blackwell unified memory optimizations
       # model_management.py: HIGH_VRAM→NORMAL_VRAM, intermediate_device()→cuda, soft_empty_cache skip,
@@ -114,7 +115,7 @@ services:
 
     volumes:
       # Share output directory with ComfyUI for gallery feature (read-only)
-      - ${SPARKYUI_DATA_PATH}/output:/shared/output:ro
+      - ${SPARKYUI_DATA_PATH:-.}/output:/shared/output:ro
       # Persist server-side workflows
       - comfyuimini_workflows:/app/workflows
 
@@ -127,6 +128,42 @@ services:
 
     restart: unless-stopped
 
+  # Model Manager - StabilityMatrix-style model download/management UI
+  # Access at http://<host>:8189
+  model-manager:
+    build:
+      context: ./model-manager
+      dockerfile: Dockerfile
+
+    image: sparkyui-model-manager:latest
+    container_name: model-manager
+
+    ports:
+      - "${MODEL_MANAGER_PORT:-8189}:8189"
+
+    environment:
+      MODELS_DIR: /models
+      DATA_DIR: /data
+
+    volumes:
+      # Shared models dir - read-WRITE here so downloads land on the host.
+      # ComfyUI mounts the same host folder read-only and picks up new files.
+      - ${COMFYUI_HOST_PATH:-.}/models:/models
+      # Persistent SQLite DB (sources, API keys, download history)
+      - ${SPARKYUI_DATA_PATH:-.}/sparkyui-data:/data
+
+    networks:
+      - sparky_net
+
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost:8189/api/model-types"]
+      interval: 30s
+      timeout: 10s
+      start_period: 15s
+      retries: 3
+
+    restart: unless-stopped
+
 networks:
   sparky_net:
     driver: bridge