docs: update feature documentation and technical details

Update the "Last Updated" date to July 15, 2026, across all localized feature documents (ES, EN, PT-BR).

In the technical English documentation, the following updates were made:
- Clarified the configuration path for Mega Hub for Meta credentials.
- Detailed provider-specific connection statuses for WAHA, Evolution, and Uazapi.
- Refined the technical flow and status states for WAHA passkey linking.
- Added documentation for the `auto_assign_on_agent_reply` setting in inboxes.