feat(ext-api): storage Wasabi de mídia — thumbnails + flag de recuperabilidade

- re-download persiste a mídia no Wasabi e gera thumbnail <url>.thumb.webp (sharp)
- GET /inbox/:chatId/messages expõe mediaRecoverable = url|path|payload presente
- ws-bridge: encaminha hook ext:presence

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

newwhats.clube67.com/newwhats.local/plugins/ext-api/backend/ws-bridge.ts

@@ -109,6 +109,7 @@ export function buildWsBridge(
       { hook: 'ext:session.status', wsEvent: 'session.status'       },
       { hook: 'ext:message.new',    wsEvent: 'message.new'          },
       { hook: 'ext:message.update', wsEvent: 'message.update'       },
+      { hook: 'ext:presence',       wsEvent: 'presence'             },
       { hook: 'ext:handoff',        wsEvent: 'conversation.handoff'   },
       { hook: 'ext:escalated',     wsEvent: 'conversation.escalated' },
     ]