chatwoot integration: Shift+Enter appends a trailing "/" and Enter inserts excessive line spacing

[milesibastos]

Summary

Multi-line messages composed in Chatwoot arrive corrupted on WhatsApp when the inbox is served
by this Evolution instance:

• Shift + Enter (soft line break) → the message arrives with a trailing /.
• Enter → excessive blank spacing between lines.

Reported on tenant mobilemed (Fizzy card evolution-foundation#14, 2026-04-15). Evolution is live for
guandalini, mobilemed, and reali.

Why this is scoped here and not to Chatwoot

Chatwoot's Channel::Api performs no outbound content transformation — the model
(app/models/channel/api.rb) holds only webhook/HMAC configuration and delivers
message.content verbatim to the configured webhook_url. For contrast, Chatwoot does
transform for channels that need it (Channel::Telegram#convert_markdown_to_telegram_html),
and no such method exists for the API channel.

So the content leaves Chatwoot with its original \n line breaks, and the corruption happens
downstream. Starting point: src/api/integrations/chatbot/chatwoot/services/chatwoot.service.ts.

Verified by reading chatwoot-app @ 6f3a9c7b9c; re-check if the API channel gains a transform
later.

Steps to reproduce

1. Open a WhatsApp conversation on a Chatwoot inbox wired to this Evolution instance.
2. Compose a message with several lines, using Shift + Enter for the breaks.
3. Send it and read the result on the recipient's WhatsApp.

Acceptance check

A message composed with Shift + Enter arrives on WhatsApp with exactly the line breaks that were
typed, with no trailing / and no inserted blank lines.

Caveat

Reported ~3 months ago. Confirm it still reproduces on the current image before fixing — the
upstream integration has had releases since.