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

web/src/lib/components/AddToPlaylistMenu.svelte

@@ -3,7 +3,7 @@
   import { useQueryClient } from '@tanstack/svelte-query';
   import { createPlaylistsQuery, appendTracks, createPlaylist } from '$lib/api/playlists';
   import { qk } from '$lib/api/queries';
-  import { copyForCode } from '$lib/api/error-copy';
+  import { errMessage } from '$lib/api/errors';
   import TrackMenuItem from './TrackMenuItem.svelte';
   import TrackMenuDivider from './TrackMenuDivider.svelte';
   import type { TrackRef } from '$lib/api/types';
@@ -37,8 +37,7 @@
       await queryClient.invalidateQueries({ queryKey: qk.playlists() });
       onClose();
     } catch (e: unknown) {
-      const code = (e as { code?: string })?.code ?? 'unknown';
-      error = copyForCode(code);
+      error = errMessage(e);
     } finally {
       busy = false;
     }
@@ -57,8 +56,7 @@
       await queryClient.invalidateQueries({ queryKey: qk.playlists() });
       onClose();
     } catch (e: unknown) {
-      const code = (e as { code?: string })?.code ?? 'unknown';
-      error = copyForCode(code);
+      error = errMessage(e);
     } finally {
       busy = false;
     }