Every window shares one server settings document, and every PUT returns the
merged whole, so one window's activeProjectId write was adopted by the
other on its next unrelated settings save — its sidebar then auto-selected
a session in that project and wrote the pointer back, converging both
windows onto one session. settings-synced now carries an adoptWorkspace
flag: only bootstrap-grade syncs (startup, runtime switch) may adopt the
shared workspace pointers; reconcile responses keep the window's own active
project while it exists. Notification clicks and session deep links also
stopped broadcasting the session switch to every window.