Discovered while verifying the sync design with the user: these two
exported methods are dead in production (only FullSync's *Core calls
are actually used), kept alive only by tests, and their doc comments
still reference the background sync loop removed in 4d2cbe4.
Phase-aware sync progress (discovering/activities/workouts), a new
/api/sync/status shape, and a blocking SyncModal replacing the Profile
page's inline sync text -- implementing the "improve synchronization"
idea from docs/IDEAS.md.
