Add ComfyUIMini mobile-friendly UI integration

New features:
- ComfyUIMini container (Node.js Alpine, ~150MB) for mobile/tablet access
- Separate container architecture with shared Docker network
- Health checks on both services with proper dependency ordering
- Shared output volume for image gallery feature

Files added:
- comfyuimini/Dockerfile - Node.js 20 Alpine with tsx runtime
- comfyuimini/.dockerignore - Build context filtering

Files updated:
- docker-compose.yml - Added comfyuimini service, network, health checks
- .env.example - Added COMFYUIMINI_PORT and COMFYUIMINI_REF
- README.md - Architecture diagram, ComfyUIMini docs, updated credits

Access points:
- ComfyUI (Desktop): http://<host>:8188
- ComfyUIMini (Mobile): http://<host>:3000

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.env.example

@@ -20,3 +20,8 @@ COMFYUI_FLAGS=--listen 0.0.0.0 --port 8188 --disable-pinned-memory --force-fp16
 # Build refs (pin to specific commits/tags for reproducibility)
 COMFYUI_REF=master
 SAGEATTN_REF=main
+
+# ComfyUIMini - Mobile-friendly UI (optional)
+# Access at http://<host>:3000
+COMFYUIMINI_PORT=3000
+COMFYUIMINI_REF=main