fix(test): mock load method in hashtagPreferences service

- Add `load: async () => {}` stub to `baseHashtagPreferences` in `tests/profile-modal-controller.test.mjs` to prevent `TypeError` during `handleAddHashtagPreference` test.
- Fixes CI failure in `tests/profile-modal-controller.test.mjs` where `this.hashtagPreferencesService.load` was undefined.
- Verified with `npm run test:unit:shard3`.

Co-authored-by: PR0M3TH3AN <[email protected]>

tests/profile-modal-controller.test.mjs

@@ -273,6 +273,7 @@ function createController(options = {}) {
       }
       return hashtagStore.disinterests.delete(normalized);
     },
+    load: async () => {},
     publish: async () => ({ ok: true }),
     on: () => () => {},
   };