Render vendor-model photos on asset detail heroes

Computer and Printer payloads now surface the linked model imageurl the
way machines already did, and the machine/PC/printer detail heroes
render the photo when present (network devices and measuring tools
have no model link, so nothing to surface). Absent images render
nothing rather than a broken icon.

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

frontend/src/views/pcs/PCDetail.vue

@@ -13,6 +13,9 @@
     <template v-else-if="computer">
       <!-- Hero Section -->
       <div class="hero-card">
+        <div class="hero-image" v-if="computer.computer?.imageurl">
+          <img :src="computer.computer.imageurl" :alt="computer.computer.modelname || 'Model photo'" />
+        </div>
         <div class="hero-content">
           <div class="hero-title">
             <h1>{{ computer.assetnumber }}</h1>