v0.16.0

Added

• Added daemon-mode plane-concurrent scheduling. Default modes remain serial,
  while learning-enabled modes can run one Learning stage concurrently with one
  permitted foreground Planning or Execution stage under the compiled
  concurrency policy.
• Added plane-indexed active-run status output and queue active counts for
  learning requests.

Changed

• Runtime active state is now canonicalized in active_runs_by_plane; legacy
  active_* snapshot fields remain as a foreground compatibility projection.
• Daemon result application remains single-writer even when stage runner
  workers are running concurrently.
• Config reloads are deferred while active planes exist and are applied after
  active runs drain.