feat(hachidori): derive Docker management URL from the linked host

- Default character dictionary uploads to the linked host on port 8780; externalHostManagementUrl is now an optional override
- Warn when the override points at a different machine than the link
- Browser/app hosts report where to import the merged ZIP manually
- Name the management origin when the upload request cannot connect
- Update config descriptions, generated examples, docs, and changelog fragment

src/config/definitions/options-core.ts

@@ -86,7 +86,7 @@ export function buildCoreConfigOptionRegistry(
       kind: 'string',
       defaultValue: defaultConfig.hachidori.externalHostManagementUrl,
       description:
-        'Docker host management URL for automatic character dictionary uploads and replacement. Empty disables external uploads.',
+        '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',