Add no-cache response header to dashboard for immediate visibility after deploys; enhance Proxmox monitoring documentation and update flash script to allow Backup without a golden image.

chromium-setup/emmc-provisioning/docs/PROXMOX-LXC-DEPLOYMENT.md

@@ -141,6 +141,32 @@ Then open **http://<LXC-201-IP>:5000** (get the IP with `pct exec 201 -- h
 
 ---
 
+## Monitoring from the host
+
+From the **Proxmox host** you can monitor:
+
+| What | How |
+|------|-----|
+| **USB device** | `lsusb` — CM4 in boot mode shows as **2b8e** (RPi) or **0a5c:2711** (Broadcom BCM2711) |
+| **Live status** | `cat /var/lib/cm4-provisioning/status.json` — same JSON the dashboard shows (phase, message, error) |
+| **Flash log** | `tail -f /var/lib/cm4-provisioning/flash.log` — script log (rpiboot, dd, errors) |
+| **Flash job** | `systemctl status cm4-flash-once` — whether the udev-triggered job is running/failed |
+| **Journal** | `journalctl -u cm4-flash-once -f` or `journalctl -t cm4-flash -f` — systemd/log output |
+| **Block devices** | `lsblk` — after rpiboot, the eMMC appears as a new disk (e.g. `/dev/sdb`) |
+| **Backups** | `ls /var/lib/cm4-provisioning/backups/` — backup images created from the dashboard |
+| **Config** | `cat /opt/cm4-provisioning/env` — GOLDEN_IMAGE, RPIBOOT_DIR, EMMC_SIZE_BYTES |
+
+**One-command snapshot:**
+
+```bash
+# From your machine (stream script to host):
+ssh root@10.130.60.224 'bash -s' < chromium-setup/emmc-provisioning/scripts/monitor-from-host.sh
+```
+
+Or copy `scripts/monitor-from-host.sh` to the host and run `./monitor-from-host.sh` for a full status dump (USB, status.json, flash unit, last log lines, block devices, config).
+
+---
+
 ## Redeploy / update scripts
 
 From your repo (e.g. after changing scripts):