Separate PokeAPI ID from national dex for correct form identification

Pokemon forms (e.g., Alolan Rattata) had their PokeAPI ID (10091) stored as
national_dex, causing them to display incorrectly. This renames the unique
identifier to pokeapi_id and adds a real national_dex field shared between
forms and their base species, so Alolan Rattata correctly shows as #19.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/hooks/useAdmin.ts

@@ -160,7 +160,7 @@ export function useDeletePokemon() {
 export function useBulkImportPokemon() {
   const qc = useQueryClient()
   return useMutation({
-    mutationFn: (items: Array<{ nationalDex: number; name: string; types: string[]; spriteUrl?: string | null }>) =>
+    mutationFn: (items: Array<{ pokeapiId: number; nationalDex: number; name: string; types: string[]; spriteUrl?: string | null }>) =>
       adminApi.bulkImportPokemon(items),
     onSuccess: (result) => {
       qc.invalidateQueries({ queryKey: ['pokemon'] })