One switch makes a laptop hot-reload what someone pushes elsewhere (e.g. cloud agents): a URL needs no
`git remote add`. Credentials in a https://user:token@ URL are never shown in the log or /api/dev-sync.
Opt-in with DX_SYNC_REMOTE (plus DX_SYNC_BRANCH, default main, and DX_SYNC_INTERVAL, default 15 s) in
.env.local. Every interval the dev server fetches the branch and fast-forwards when this checkout is on it
with no modified tracked files and no local commits, so Vite hot-reloads what teammates landed. Otherwise
it never merges, stashes or resets: it logs once and reports "main is N commits ahead, pull when ready" at
/api/dev-sync for a Studio badge.
