Overview: network status pill for the two NICs

A 'Network' pill next to 'Services' lists each physical NIC with its role
(imaging / GE network, from /etc/pxe-server/nic.conf or dnsmasq's
interface= pin), link, speed, addresses, and whether dnsmasq serves
DHCP/PXE on it. It reads pxe-nic-check's verdict file
(/run/pxe-nic-status.json) when present, and shows a red banner when the
imaging NIC is on the GE network or a network with another DHCP server,
or when dnsmasq answers DHCP on a non-imaging NIC. Without the file it
shows link and addresses only. Read-only.

webapp/app.py

@@ -56,6 +56,7 @@ from services import (
     images,
     imaging_status,
     mcl_ppkg,
+    nic_status,
     system,
     unattend,
     wim,
@@ -113,6 +114,11 @@ def dashboard():
             img["os_label"], img["driver_count"] = "", 0
         img["lint"] = image_pages._lint_counts(img["image_type"])
     services = [system.service_status(s) for s in ("dnsmasq", "apache2", "smbd")]
+    try:
+        nic = nic_status.status()
+    except Exception:  # the page must render even if this breaks
+        app.logger.exception("network status failed")
+        nic = None
     sessions, _hidden = imaging_status.hide_stale(imaging_status.list_sessions())
     floor = imaging_status.floor_order(sessions)
     real = [x for x in floor if x["floor_state"] != "logs"]
@@ -121,6 +127,7 @@ def dashboard():
         "dashboard.html",
         images=image_list,
         services=services,
+        nic=nic,
         image_types=config.IMAGE_TYPES,
         friendly_names=config.FRIENDLY_NAMES,
         sessions=real[:6],