R-729 + R-545: the household can remove its own off-site target („Távoli mentési cél törlése")

POST /backup/offbox/clear (reveal-then-confirm) forgets the target and deletes ssh_key + known_hosts;
nothing on the target is touched. repo_password is kept whenever anything could depend on it (hub
sealed package — the R-241 rule; escrowed; a successful run; snapshots) and deleted only otherwise.
Refused for the Felhom tier (rclone-pinned), while the single-flight is held, and while an
abandonment countdown runs. i18n parity fixtures of backups_remote gain the additive block only.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/testdata/i18n_parity/backups_remote_notconf.html

@@ -213,6 +213,8 @@
             <button type="submit" class="btn btn-sm btn-primary" style="margin-top:.5rem">Mentés</button>
         </form>
     </details>
+    
+    
 </div>