refactor(hachidori): drop the Docker management upload for character dictionaries

Every supported host now takes dictionary ZIPs over the link, so remove
the port 8780 upload, its hachidori.externalHostManagementUrl override and
the hachidori config section. A linked host without linked-import-v1 now
reports the update or manual-import fix.

src/config/definitions/options-core.ts

@@ -81,13 +81,6 @@ export function buildCoreConfigOptionRegistry(
   ] as const;
 
   return [
-    {
-      path: 'hachidori.externalHostManagementUrl',
-      kind: 'string',
-      defaultValue: defaultConfig.hachidori.externalHostManagementUrl,
-      description:
-        'Management URL override for character dictionary uploads to a linked Hachidori Docker host. Empty uses the linked host on the Docker default management port.',
-    },
     {
       path: 'dictionaryBackend',
       kind: 'enum',