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

services/zfs.py

@@ -0,0 +1,42 @@
+import asyncio
+import os
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+async def get_zfs_pool_map() -> dict[str, str]:
+    """Return a dict mapping device names to ZFS pool names.
+
+    e.g. {"sda": "tank", "sdb": "tank", "sdc": "fast"}
+    """
+    pool_map = {}
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            "zpool", "status", "-P",
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+        stdout, _ = await proc.communicate()
+        if proc.returncode != 0:
+            return pool_map
+
+        current_pool = None
+        for line in stdout.decode().splitlines():
+            stripped = line.strip()
+            if stripped.startswith("pool:"):
+                current_pool = stripped.split(":", 1)[1].strip()
+            elif current_pool and "/dev/" in stripped:
+                parts = stripped.split()
+                dev_path = parts[0]
+                try:
+                    real = os.path.realpath(dev_path)
+                    dev_name = os.path.basename(real)
+                    # Strip partition numbers (sda1 -> sda)
+                    dev_name = dev_name.rstrip("0123456789")
+                    pool_map[dev_name] = current_pool
+                except Exception:
+                    pass
+    except FileNotFoundError:
+        logger.debug("zpool not available")
+    return pool_map