Archive, part 3b: Wake restarts an archived app's production from the default branch on the same data #2457

Part 2 of #1840.

Done looks like:

• [ ] Waking a repository restarts production from the default branch on the same data directory. Previews come back on their pull's next push.
• [ ] Test: data written before archiving is served again after Wake. Run test/apps.test.ts and quote the result.