fix: validate logo index entries before building URLs

Guard against path traversal and unexpected file types by
validating logo paths start with 'logo/', have allowed image
extensions, and contain no '..' or leading '/' segments.

Amp-Thread-ID: https://ampcode.com/threads/T-019c083e-8ba0-7699-a5ff-63fd03e24391
Co-authored-by: Amp <amp@ampcode.com>

src/platform/workflow/templates/repositories/workflowTemplatesStore.ts

@@ -515,7 +515,15 @@ export const useWorkflowTemplatesStore = defineStore(
 
     function getLogoUrl(provider: string): string {
       const logoPath = logoIndex.value[provider]
-      if (!logoPath) return ''
+      if (
+        !logoPath ||
+        logoPath.includes('..') ||
+        logoPath.startsWith('/') ||
+        !logoPath.startsWith('logo/') ||
+        !/\.(png|svg|jpg|jpeg)$/i.test(logoPath)
+      ) {
+        return ''
+      }
       return api.fileURL(`/templates/${logoPath}`)
     }