Fillets and chamfers ending on a boss's pieced wall or beside it, on a face that runs along its seam twice, and loops the loop blend refuses (#926)

Fillets and chamfers ending on a boss's pieced wall or beside it, on a face that runs along its seam twice, and loops the loop blend refuses

- A straight edge whose end meets one curved surface in several faces (a cylinder a join left
  in pieces) ends on that surface: the section is cut where it crosses each seam, which is
  shortened there; where no seam is crossed (the wall missing inside the other body) the
  section lies on the bared surface and the rest of the side edge becomes a seam.
- Two end faces that aren't both planes meeting in lines: each face takes the section's points
  on it, cut where it crosses the edge between them. Not where an end face runs on smoothly
  from a side (an earlier round): the corner build takes those.
- Face boundaries close over several connector edges.
- A face on a periodic surface running along its seam twice (as a STEP file gives it) is
  rebuilt the same way (#691).
- A curved chain ending square on a face that runs on past its side extends that face's seam.
- A smooth chain stops before an edge between faces that meet smoothly.
- A loop the loop blend refuses for its shape is blended edge by edge; refusals about its size
  stand.
- Action matrix: ACTION_MATRIX_ACTIONS and ACTION_MATRIX_VALIDITY for quick local runs; the
  fillets and chamfers that pass now recorded.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/action-matrix.md

@@ -18,6 +18,9 @@ The test is [`apps/solidcraft-cli/tests/action_matrix.rs`](../apps/solidcraft-cl
   `--results FILE` to keep every outcome with its message and the command that was sent.
   `ACTION_MATRIX_FILTER=oracle/23` runs only the designs whose name contains it;
   `ACTION_MATRIX_JOBS` sets how many designs run at once.
+  For a quick local look, `ACTION_MATRIX_ACTIONS=edge.fillet,edge.chamfer` tries only those actions (never
+  bless such a run) and `ACTION_MATRIX_VALIDITY=1` adds each passing action's body check (`Body::validity`)
+  to the results.
 
 Each design runs in its own process, so an action that hangs (90 s without a result) or aborts is
 recorded as `timeout` or `crash` and the rest of the design still runs. Loading a design, before