feat(books): surface custom metadata fields in table view

Adds support for displaying custom metadata as columns in the book
table view. The frontend now fetches active fields and dynamically
renders the corresponding cells, backed by book card API updates.

Closes #465

client/src/features/book/components/table/BookTableCollapsedSeriesCell.vue

@@ -3,12 +3,11 @@ import { computed } from 'vue'
 import { ChevronRight, LibraryBig } from '@lucide/vue'
 import { FORMAT_TO_GROUP, type BookCard } from '@bookorbit/types'
 import BookCoverSurface from '../BookCoverSurface.vue'
-import type { ColumnId } from '@/features/book/composables/useTableColumns'
 import { useCoverVersions } from '@/features/book/composables/useCoverVersions'
 
 const props = defineProps<{
   book: BookCard
-  colId: ColumnId
+  colId: string
 }>()
 
 const collapsed = computed(() => props.book.collapsedSeries!)