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>

scripts/import-masstimes-api.ts

@@ -398,7 +398,6 @@ async function loadExistingChurches(): Promise<ExistingChurch[]> {
       miserendId: true,
       kerknetId: true,
       gottesdienstzeitenId: true,
-      discovermassId: true,
       source: true,
       website: true,
       phone: true,
@@ -596,7 +595,7 @@ async function main() {
                 orarimesseId: null, massSchedulesPhId: null,
                 philmassId: null, horariosMisasId: null,
                 mszeInfoId: null, weekdayMassesId: null,
-                messesInfoId: null, bohosluzbyId: null, miserendId: null, kerknetId: null, gottesdienstzeitenId: null, discovermassId: null,
+                messesInfoId: null, bohosluzbyId: null, miserendId: null, kerknetId: null, gottesdienstzeitenId: null,
                 source: 'masstimes', website: mc.url?.trim() || null,
                 phone: mc.phone_number?.trim() || null, address, country,
               });