v0.3.0

fix: bind upload sessions to their target, keep pending scans in sync

- Resumable sessions record file id, parent, name, precondition and content
  hash; a session is resumed only for the exact plan it was opened for, and
  the returned identity is verified before success is recorded
- Pending folder scans follow renames and removals, resolve their path by id
  when they run, and a vacated path queues a shallow re-list of its parent so
  a suppressed duplicate is rediscovered
- Subtree pushes verify every cached ancestor before creating a folder
- Session persistence errors fail the upload instead of being ignored
- Regression suite against a loopback Drive fixture

Signed-off-by: Rohit Yadav <rohit@scaleninja.com>