refactor(web/api): errCode + errMessage helpers; 41 sites migrated (W1)

web/src/lib/components/RemoveTrackPopover.svelte

@@ -2,7 +2,7 @@
   import { Trash2 } from 'lucide-svelte';
   import { useQueryClient } from '@tanstack/svelte-query';
   import { removeTrack } from '$lib/api/admin/tracks';
-  import { copyForCode } from '$lib/api/error-copy';
+  import { errMessage } from '$lib/api/errors';
   import { qk } from '$lib/api/queries';
   import type { TrackRef } from '$lib/api/types';
 
@@ -45,8 +45,7 @@
       // surface (if any) can pick up the flag.
       onClose();
     } catch (e: unknown) {
-      const code = (e as { code?: string })?.code ?? 'unknown';
-      error = copyForCode(code);
+      error = errMessage(e);
     } finally {
       busy = false;
     }