Thread stages v0.7.0

Minor Changes

• 814341b: Adapt Thread stages to different workflows with configurable message previews,
  optional Deferred and Blocked stages, and automatic archival of Completed thread
  hierarchies after 1, 7, or 30 days. Auto-archive defaults to 7 days, preserves
  pinned hierarchies, and can be disabled. Rows without previews now shrink to the
  same height as bb's built-in thread rows.

Patch Changes

• 1600e04: Call the section-less bucket Unorganized, the way bb calls it. The filter and the
  Move to section submenu said Uncategorized, a word bb uses nowhere — its sidebar
  group is labeled Unorganized, and its own remove-section dialog says threads
  "will move back to Unorganized", which this plugin already repeats verbatim one
  component over. Only the wording moves; the saved filter keeps its stored value,
  so a client filtered to that bucket stays filtered to it.