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.js

@@ -91,6 +91,7 @@ function buildWsBridge(httpServer, prisma, hooks) {
             { 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' },
         ];