Reciprocal controls links, dead chip links, and a resumable legacy import

The machine page now shows the PC that controls it. The endpoint was correct all
along and returned both directions; AssetTriageBand discarded every peer whose
type was not 'machine' and was mounted only on the PC page. The counterpart type,
label and relationship types are now props.

Fixed while adopting it more widely: every band chip linked to /assets/<id>, and
there is no such route. The resolver that AssetRelationships.vue kept privately
is now frontend/src/utils/assetRoute.js, used by both - and its type lookup is
case-insensitive, because seed data capitalises the type names while this site's
database does not.

The legacy import is now safe to resume. The 409-resolve asked for
per_page=10000 against a server that clamps to 100, so it silently searched the
first 100 rows and dropped links past that on every re-run. The crosswalk is now
bound to the database it describes, so one carried across a rebuild is refused
rather than attaching rows to the wrong assets. Source database names are
resolved from the environment, so the loader can be aimed without editing it.

Full suite 2178 passed, frontend 280 passed.

plugins/printers/frontend/views/PrinterDetail.vue

@@ -66,6 +66,16 @@
               <span class="hero-detail-value mono">{{ ipAddress }}</span>
             </div>
           </div>
+
+          <!-- The 6am band: which machine stops if this printer is down.
+               A shop-floor printer is often a label or tag printer feeding one
+               machine, and that link was only visible in the relationships
+               card near the bottom of the page. -->
+          <AssetTriageBand
+            :assetid="printer.assetid"
+            counterparttype="machine"
+            :relationshiptypes="['usesprinter', 'defaultprinter']"
+          />
         </div>
       </div>
 
@@ -301,6 +311,7 @@ import { useRoute, useRouter } from 'vue-router'
 import { printersApi } from '@/api'
 import { withBase } from '@/utils/basePath'
 import LocationMapTooltip from '@/components/LocationMapTooltip.vue'
+import AssetTriageBand from '@/components/AssetTriageBand.vue'
 import CustomFieldsSection from '@/components/CustomFieldsSection.vue'
 import PluginAssetPanels from '@/components/PluginAssetPanels.vue'
 import AssetRelationships from '@/components/AssetRelationships.vue'