Initial Meterbox commit with boot disk usage metric.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -0,0 +1,30 @@
+services:
+  meterbox:
+    build: .
+    container_name: meterbox
+    restart: unless-stopped
+    # Host network + bind 127.0.0.1 inside the app:
+    # - accurate host NIC / load metrics
+    # - no Docker published ports (avoids DNAT bypass of INPUT REJECT)
+    # - Caddy/Rathole can still reach 127.0.0.1:8787
+    network_mode: host
+    pid: host
+    volumes:
+      - ./data:/app/data
+      - /etc/os-release:/etc/os-release:ro
+      - /etc/hostname:/etc/hostname:ro
+      - /run/bwflow:/run/bwflow:ro
+      - /var/lib/vnstat:/var/lib/vnstat:ro
+      - /etc/vnstat.conf:/etc/vnstat.conf:ro
+    environment:
+      METERBOX_LISTEN: "127.0.0.1:8787"
+      METERBOX_DB: "/app/data/meterbox.db"
+      METERBOX_STATIC: "/app/frontend/dist"
+      METERBOX_INTERVAL_SECS: "30"
+      METERBOX_RETENTION_DAYS: "90"
+      # Hard cap: 10 GiB for SQLite (db + wal + shm). Cleanup job trims oldest rows.
+      METERBOX_MAX_DB_BYTES: "10737418240"
+      METERBOX_CLEANUP_INTERVAL_SECS: "3600"
+      METERBOX_BWFLOW_SOCK: "/run/bwflow/bwflow.sock"
+    security_opt:
+      - no-new-privileges:true