Consolidate asset relationships onto the shared card

The curated Controlled Machines (PC detail) and Connected PC (machine
detail) cards duplicated what the generic relationships card already
shows with type badges and inline add/remove - and hid every
non-controls relationship type. Removed the curated cards and their
plumbing (~105 lines of orphaned CSS included); the MachineForm
controlling-PC picker stays as the write path. Also theme-variable
fixes on the shared card styling.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/views/machines/MachineDetail.vue

@@ -183,30 +183,6 @@
             </div>
           </div>
 
-          <!-- Connected PC -->
-          <div class="section-card">
-            <h3 class="section-title">Connected PC</h3>
-            <div v-if="!controllingPc" class="empty-message">
-              No controlling PC assigned
-            </div>
-            <div v-else class="connected-device">
-              <router-link :to="`/pcs/${controllingPc.pluginid || controllingPc.assetid}`" class="device-link">
-                <div class="device-icon">
-                  <svg xmlns="http://www.w3.org/2000/svg" width="24" height="24" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
-                    <rect x="2" y="3" width="20" height="14" rx="2" ry="2"></rect>
-                    <line x1="8" y1="21" x2="16" y2="21"></line>
-                    <line x1="12" y1="17" x2="12" y2="21"></line>
-                  </svg>
-                </div>
-                <div class="device-info">
-                  <span class="device-name">{{ controllingPc.assetnumber }}</span>
-                  <span class="device-alias" v-if="controllingPc.name">{{ controllingPc.name }}</span>
-                </div>
-              </router-link>
-              <span class="connection-type">{{ controllingPc.relationshipType }}</span>
-            </div>
-          </div>
-
           <!-- Custom Fields -->
           <CustomFieldsSection :assetid="machine.assetid" />
 
@@ -238,9 +214,9 @@
 </template>
 
 <script setup>
-import { ref, computed, onMounted } from 'vue'
+import { ref, onMounted } from 'vue'
 import { useRoute } from 'vue-router'
-import { machinesApi, assetsApi } from '../../api'
+import { machinesApi } from '../../api'
 import LocationMapTooltip from '../../components/LocationMapTooltip.vue'
 import CustomFieldsSection from '../../components/CustomFieldsSection.vue'
 import WarrantyPanel from '../../components/WarrantyPanel.vue'
@@ -254,54 +230,13 @@ const { isEnabled } = useIdentifierFlags()
 const loading = ref(true)
 const machine = ref(null)
 const { warranties, heroWarranty, warrantyDate } = useWarrantyBadge(() => machine.value?.assetid)
-const relationships = ref({ incoming: [], outgoing: [] })
 
-// type name is data, sites may seed 'controls' or 'Controls' - compare folded
-function isControls(rel) {
-  return (rel.relationshiptypename || '').toLowerCase() === 'controls'
-}
-
-const controllingPc = computed(() => {
-  // For a machine, find a related computer in any "Controls" relationship
-  // Check both incoming (computer controls this) and outgoing (legacy data may have machine -> computer)
-
-  // First check incoming - computer as source controlling this machine
-  for (const rel of relationships.value.incoming || []) {
-    if (rel.sourceasset?.assettypename === 'computer' && isControls(rel)) {
-      return {
-        ...rel.sourceasset,
-        relationshipType: rel.relationshiptypename
-      }
-    }
-  }
-
-  // Also check outgoing - legacy data may have machine -> computer Controls relationships
-  for (const rel of relationships.value.outgoing || []) {
-    if (rel.targetasset?.assettypename === 'computer' && isControls(rel)) {
-      return {
-        ...rel.targetasset,
-        relationshipType: rel.relationshiptypename
-      }
-    }
-  }
-
-  return null
-})
+// relationships render via the shared AssetRelationships card
 
 onMounted(async () => {
   try {
     const response = await machinesApi.get(route.params.id)
     machine.value = response.data.data
-
-    // Load relationships using asset ID
-    if (machine.value?.assetid) {
-      try {
-        const relResponse = await assetsApi.getRelationships(machine.value.assetid)
-        relationships.value = relResponse.data.data || { incoming: [], outgoing: [] }
-      } catch (e) {
-        console.log('Relationships not available')
-      }
-    }
   } catch (error) {
     console.error('Error loading machine:', error)
   } finally {