fix(fuse): put a deadline on every remote call the drain makes

create_folder, trash_nodes, the twin listing and the uploads waited on
Drive without a limit, so one call that never answered held a drain
thread for good. They now give up after INTERACTIVE_CALL_TIMEOUT, and
uploads after that plus their size at 32 KiB/s; a missed deadline reads
as RequestTimeout, so the op backs off like any lost link.

docs/CHANGELOG.md

@@ -31,6 +31,9 @@ are kept. Queued changes get a column for the reason Drive refused them.
   for this release.
 
 ### Fixed
+- **A queued change no longer holds up the queue forever on a link that stops answering.**
+  Sending a new folder, a delete or a file waits at most 20 seconds for Drive, plus time for
+  the file's size, and then the queue treats the link as down and tries again.
 - **A file deleted while its first upload is on the wire no longer stays on Drive.** The node
   the upload made is trashed as soon as it lands, so its name is free again (B129).
 - **A delete queued while a rename is sent is no longer lost.** The rename landing could remove

docs/MILESTONE-3.0.0-STATUS.md

@@ -50,7 +50,8 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
   3.0.0).
 - **Phase 4**: one applier for remote changes.
 - **Phase 5**: mirror folders on the same planner and executor.
-- **Any time**: `Size` and block geometry as types; a `Deadline` on every remote call.
+- **Any time**: `Size` and block geometry as types; a deadline on the remote calls outside
+  the drain (the drain's have one: `link::upload_deadline`, `Core::block_on_within`).
 - Open questions in §12 of the milestone.
 - `PLAN.md`: the acceptance script notices network drops and reports `interrupted` instead of
   TIMEOUT.