Add minimal-reproduction and fixed-point-verification reasoning protocols (#223)

* Add minimal-reproduction and fixed-point-verification reasoning protocols

New components:

- protocols/reasoning/minimal-reproduction.md: 4-phase bug isolation
  methodology — construct minimal reproduction, binary simplification
  (strip features one at a time), pivot point identification (find
  the boundary between working and broken), root cause confirmation.
  Addresses #209.

- protocols/reasoning/fixed-point-verification.md: 4-phase
  transformation correctness verification — define the transformation
  and convergence expectation, execute the fixed-point test (apply
  twice, compare), diagnose divergence (semantic/syntactic/additive),
  verify convergence with resource and coverage checks. Applicable to
  formatters, compilers, generators, migrators, and serializers.
  Addresses #211.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Address review: fix description conflation, add multi-pass convergence

- fixed-point-verification description: replace 'does not faithfully
  preserve semantics' with 'does not reach a fixed point' — syntactic
  divergence doesn't break semantics, only idempotency.
- fixed-point-verification Phase 2: add multi-pass iteration (up to
  7 total passes) for transformations that converge after >2 passes.
  Prevents false FAILs for multi-pass normalizers.
- Phase 3 intro: remove assumption that divergence is always a bug.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Alan Jowett <alan.jowett@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>