Add React frontend, ZFS pool mapping, and multi-stage Docker build

- Vite + React frontend with dark-themed dashboard, slot grid per
  enclosure, and SMART detail overlay
- ZFS pool membership via zpool status -P
- Multi-stage Dockerfile (Node build + Python runtime)
- Updated docker-compose with network_mode host and healthcheck

main.py

@@ -1,8 +1,11 @@
 import logging
 import os
+from pathlib import Path
 
 from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import FileResponse
+from fastapi.staticfiles import StaticFiles
 
 from models.schemas import HealthCheck
 from routers import drives, enclosures, overview
@@ -50,3 +53,18 @@ async def check_dependencies():
 @app.get("/api/health", response_model=HealthCheck, tags=["health"])
 async def health():
     return HealthCheck(status="ok", tools=_tool_status)
+
+
+# Serve built frontend static files (must be after all /api routes)
+STATIC_DIR = Path(__file__).parent / "static"
+
+if STATIC_DIR.exists():
+    app.mount("/assets", StaticFiles(directory=STATIC_DIR / "assets"), name="assets")
+
+    @app.get("/{full_path:path}")
+    async def serve_spa(full_path: str):
+        """Catch-all: serve index.html for SPA routing."""
+        file_path = STATIC_DIR / full_path
+        if file_path.is_file():
+            return FileResponse(file_path)
+        return FileResponse(STATIC_DIR / "index.html")