Add photo management for models and employees; fix stale detail navigation

Model photos: upload/replace/delete on /api/models/<id>/image (admin),
stored under instance/modelimages/ with a public serve route; thumbnail
plus Upload/Replace/Remove controls in the Models settings modal; the
URL field remains as a manual alternative.

Employee photos, mode-aware: self-hosted directory employees get
upload/replace/delete (photo-<sso> under instance/employeephotos/,
employees plugin migration 0002); external directory mode passes the
HR-supplied picture URL through read-only (writes 409). One resolver
feeds both consumers - the shopfloor recognition/recert kiosk cards and
the employee detail hero - in either mode.

Navigation fix: router-view is keyed on route path, so following a
relationship link between two assets of the same type (machine ->
dualpath machine) reloads the page instead of showing stale content;
query-only URL changes still avoid a remount.

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

frontend/src/api/index.js

@@ -389,6 +389,15 @@ export const modelsApi = {
   },
   delete(id) {
     return api.delete(`/models/${id}`)
+  },
+  uploadImage(id, file) {
+    // multipart photo upload; backend sets imageurl to the served URL
+    const form = new FormData()
+    form.append('file', file)
+    return api.post(`/models/${id}/image`, form, { headers: { 'Content-Type': 'multipart/form-data' } })
+  },
+  removeImage(id) {
+    return api.delete(`/models/${id}/image`)
   }
 }
 
@@ -730,6 +739,15 @@ export const employeesApi = {
     },
     importCsv(csv) {
       return api.post('/employees/directory/import', { csv })
+    },
+    // multipart photo upload; backend sets photofilename + returns photourl
+    uploadPhoto(sso, file) {
+      const form = new FormData()
+      form.append('file', file)
+      return api.post(`/employees/${sso}/photo`, form, { headers: { 'Content-Type': 'multipart/form-data' } })
+    },
+    removePhoto(sso) {
+      return api.delete(`/employees/${sso}/photo`)
     }
   }
 }