taskwarrior: DRY up export/import into symmetric label helpers

The export path passed a file_label argument that was always identical to the
tag (TASK_EXPORT_TAG/TASK_EXPORT_TAG, rocky/rocky), and the import path
duplicated the find | while read | import/rm block once per source. Collapse
both into a single 'list of labels' model:

- _taskwarrior::export_tag drops the redundant file_label; the tag name is the
  file label.
- New _taskwarrior::import_label imports+removes all files for one label,
  replacing the two copy-pasted blocks.
- export loops over [$TASK_EXPORT_TAG rocky]; import loops over
  [$TASK_IMPORT_TAG (hostname)]. The rocky routing (export by tag name, import
  by hostname match) is now explicit and symmetric.

Behaviour is unchanged; verified with a stubbed-task/hostname harness covering
the rocky host, a non-rocky host, and label isolation.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions