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>

plugins/printers/models/printer.py

@@ -118,5 +118,7 @@ class Printer(BaseModel):
             result['vendorname'] = self.vendor.vendor
         if self.model:
             result['modelname'] = self.model.modelnumber
+            if self.model.imageurl:
+                result['imageurl'] = self.model.imageurl
 
         return result