Get-EpicReport gains --by, --view and --output: the thread status document #786

scripts/Get-EpicReport renders the epic / feature / task tree. Thread status needs a different shape: one
table per thread with a row number, the issue, its title, a green check when closed, and a comment carrying
the kind, the parent feature, the triage attributes and any classification fault.

• --by epic|thread picks the sections: every epic, or the one --epic names (the default); or the four
  threads in execution order (768-revised-process-setup.md, Requirement 2), which defaults --state to all
  because status includes what has closed
• --view tree|table picks the rendering: the tree as before (the default), or one status table per section
  in the same order; orthogonal to --by
• --output markdown|json is the reduced set of the output convention: markdown for a person, the default;
  json for the rows every view is built from, one object per issue
• a WIP label, if one is ever used, travels in the comment

scripts/Get-EpicReport --by thread --view table > threads.md

Resolved in #776's worktree, as its own commit.