v0.6.1

Hot-fix on v0.6.0 closing the known follow-up surfaced by the
v0.6.0 live run on paper 3bc58e8d.

Lane A — Pipeline

• Iterative-phase guard extended to drop the legacy revisor
  on iterations 2+, alongside paper_drafter. Both specialists
  rewrite paper_draft.tex from scratch every time they run, so
  the same drift argument that motivated step 6's
  paper_drafter guard applies to revisor. v0.6.0's live run
  showed the strategist dispatching revisor during iterative
  phase even though paper_drafter was correctly skipped — the
  guard only filtered one. v0.6.1 closes the same door for both.
• Strategist system prompt updated to name revisor
  explicitly alongside paper_drafter in the iterative-phase
  rule, and to point at patch_revisor (dispatched automatically
  by the runner's revision phase) as the legitimate path for
  scoped revisions. Removes the v0.6.0 ambiguity where the prompt
  said "use revisor only when upstream artifacts are updated"
  but the runner now expects no revisor calls in iterative
  phase at all.
• test_section_writer_not_dropped_on_iteration_2 renamed to
  test_legitimate_specialists_not_dropped_on_iteration_2 and
  updated to reflect the v0.6.1 contract (was asserting revisor
  survives the guard, now asserts only the legitimate specialists
  do).
• 4 new regression tests in test_iterative_phase_guard.py
  pinning the extended-guard contract.

Full mocked suite: 525 passed (was 521 in v0.6.0; +4 here).