Docs-first commit for the feature/task-sweep branch, which addresses the
bulk of the outstanding Hephaestus-project tasks in one sweep. The
fragments describe the intended end state; code follows.
Also delivers the "understand heph link wiki semantics" task outright:
the new [[wiki-links]] explanation card documents body-vs-links-table
layering, the manual-wiki-link reconciliation footgun, resolution tiers,
and per-client surfaces.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
