workspace-session-target.ts never set $newChatProfile, so a new session
started from a project's "+" reached desktopSessionCreateParams with no
intent and fell back to $activeGatewayProfile — which an in-flight profile
swap can move between the click and Send, landing session.create on the
wrong backend (#79005 flaw 3, second path). Pin the tree's profile
(projectProfile()) via the same intent write newSessionInProfile uses.
Fixes#79005
d9b051a9d6