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>

CHANGELOG.md

@@ -12,6 +12,13 @@ ADR-007 and ADR-002.
 
 ### Added
 
+- Vendor-model photos on asset detail heroes: computers and printers now
+  surface the linked model's `imageurl` in their extension payloads (the
+  field machines already exposed), and the machine, PC, printer, network
+  device, and measuring tool detail pages render the photo in the hero card
+  when present (hidden cleanly when absent). Network devices and measuring
+  tools have no model link yet, so their heroes stay photo-less until one
+  is added.
 - Dualpath "single machine" site toggle (`dualpath_single_machine`, default
   on). A Dualpath relationship pair is one physical dual-bay machine (single
   controller, bay-selector switch); when on, the machines list, dashboard and