fix: clean up church-matcher types and add HK OSM bounding box

- Remove discovermassId/buscarmisasNetworkId from findDuplicateChurch match
  passes (importers now do their own pre-check dedup); restore as optional
  fields on ExistingChurch to keep type/runtime in sync
- Add HK bounding box to COUNTRY_BOUNDING_BOXES; fix silent 0-result
  fallback when country query returns empty from mirror server
- discovermass importer: add --limit flag and skip-already-imported
  pre-check using importedSlugs set
- Import scripts: remove discovermassId from ExistingChurch select/stubs
  (field not needed in shared matcher context)
- Schema: reorder discovermassId/kerknetId/gottesdienstzeitenId fields

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

prisma/schema.prisma

@@ -42,9 +42,9 @@ model Church {
   messesInfoId          String?   @unique @map("messes_info_id")
   bohosluzbyId          String?   @unique @map("bohosluzby_id")
   miserendId            String?   @unique @map("miserend_id")
-  kerknetId             String?   @unique @map("kerknet_id")
-  gottesdienstzeitenId  String?   @unique @map("gottesdienstzeiten_id")
   discovermassId        String?   @unique @map("discovermass_id")
+  gottesdienstzeitenId  String?   @unique @map("gottesdienstzeiten_id")
+  kerknetId             String?   @unique @map("kerknet_id")
   buscarmisasNetworkId  String?   @unique @map("buscarmisas_network_id")
   claimed          Boolean   @default(false)
   claimedAt        DateTime? @map("claimed_at")
@@ -95,9 +95,9 @@ model Church {
   @@index([messesInfoId])
   @@index([bohosluzbyId])
   @@index([miserendId])
-  @@index([kerknetId])
-  @@index([gottesdienstzeitenId])
   @@index([discovermassId])
+  @@index([gottesdienstzeitenId])
+  @@index([kerknetId])
   @@index([buscarmisasNetworkId])
   @@index([dioceseId])
   @@index([claimedByUserId])