`SessionDB.resolve_session_by_title()` prefers a "`<title> #N`" continuation over the
exact match. For the canonical Bot Chat that preference is wrong: Bot Mode identifies
that session BY its exact title, and this lookup is the only one every DM transport
shares (`hermes -p <bot> chat --in ~ -c "Bot Chat"` — used by `message_agent`,
`bot_relay` and cron delivery).
Once a numbered sibling exists (a Desktop branch of the canonical chat,
`title_source='derived'`), every teammate DM resolves to that sibling: a visible,
unmanaged session where the `message_agent` gate is off, so the addressed bot cannot
answer and the sender gets silence instead of an error.
Return the exact match when the requested title IS the canonical Bot Chat title; every
other title keeps the "newest continuation wins" behaviour untouched.
(cherry picked from commit e92638b4c53c97c48db4d9bbb2d3b6b580d289a7)
06475d1138