The `fromMe` flag from Baileys' WAMessage.key was only used for
access-control filtering and then discarded. This meant agents
could not distinguish owner-sent messages from contact messages
in DM conversations (everything appeared as from the contact).
Add `fromMe` to `WebInboundMessage`, store it during message
construction, and thread it through `buildInboundLine` →
`formatInboundEnvelope` so DM transcripts prefix owner messages
with `(self):`.
Closes#32061
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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