Address jokob-sk review: shorten UI description, map scanSourcePlugin

Settings-UI description trimmed to one short line - implementation
detail (Socket Proxy, column mapping, CREATE_DEV behavior) already
lives in README, doesn't belong in the Settings page string.

scanSourcePlugin now maps to a static "DOCKERDISC" value (same
Dummy-column pattern arp_scan already uses), so a container device
created by this plugin gets devSourcePlugin set correctly instead of
NULL - every other CurrentScan-mapped plugin already does this.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011meLPKCzVpdZyAUfv5U6mm

server/plugins/dockerdisc/README.md

@@ -196,12 +196,15 @@ whether it has a real LAN-visible identity to show:
   authoritative for the host's identity and discovery-source attribution.
   A container with its own macvlan/ipvlan MAC always maps to `CurrentScan`
   (`DOCKERDISC_IMPORT_ON` permitting) - with `DOCKERDISC_CREATE_DEV` on,
-  it can originate a brand-new device; either way, if that MAC is already
-  a device (found independently by ARP/Nmap, since it's LAN-visible), this
-  plugin's row still confirms its presence and updates its
-  `devLastIP`/`devParentMAC` on every run. Turn `DOCKERDISC_IMPORT_ON` off
-  to skip all of that and keep this plugin purely informational (its
-  `Plugins_Objects` listing still updates either way) - see [Plugin Import
+  it can originate a brand-new device (`devSourcePlugin` set to
+  `DOCKERDISC` at creation, like any other `CurrentScan`-mapped plugin);
+  either way, if that MAC is already a device (found independently by
+  ARP/Nmap, since it's LAN-visible), this plugin's row still confirms its
+  presence and updates its `devLastIP`/`devParentMAC` on every run - that
+  existing device's own `devSourcePlugin` isn't touched, since it's only
+  set once, at creation. Turn `DOCKERDISC_IMPORT_ON` off to skip all of
+  that and keep this plugin purely informational (its `Plugins_Objects`
+  listing still updates either way) - see [Plugin Import
   Behavior](../../../docs/PLUGINS_IMPORT_BEHAVIOR.md).
 - Only Socket Proxy permissions required: `CONTAINERS=1` (list containers,
   their networks and labels), `INFO=1` (host-MAC auto-detection), and

server/plugins/dockerdisc/config.json

@@ -25,7 +25,7 @@
   "description": [
     {
       "language_code": "en_us",
-      "string": "Enriches known Docker hosts with their running containers - image, Compose project/service, network, MAC/IP. Optionally creates devices for LAN-visible containers; via a read-only Docker Socket Proxy."
+      "string": "Enriches known Docker hosts with their running containers."
     }
   ],
   "params": [
@@ -264,6 +264,27 @@
         }
       ]
     },
+    {
+      "column": "Dummy",
+      "mapped_to_column": "scanSourcePlugin",
+      "mapped_to_column_data": {
+        "value": "DOCKERDISC"
+      },
+      "css_classes": "col-sm-2",
+      "show": false,
+      "type": "none",
+      "default_value": "",
+      "options": [],
+      "localized": [
+        "name"
+      ],
+      "name": [
+        {
+          "language_code": "en_us",
+          "string": "N/A"
+        }
+      ]
+    },
     {
       "column": "userData",
       "css_classes": "col-sm-2",