docs(reviewer): anonymise reviewer references; profile-based framing

Replaces the "Springborn / Bobenko alumnus" placeholder in the reviewer
materials (briefing, questions, agenda, README) and in
locked-vs-flexible.md with a research-profile description:

  active researcher in the decorated-DCE / Penner-coordinates /
  canonical-tessellations / hyperideal-polyhedra line, treated as a
  peer most likely to USE conformallab++ as numerical infrastructure
  for their own future experiments — not merely to evaluate it.

Citations to the published literature (Springborn 2020 paper, etc.)
remain untouched.  Only personal references to the prospective
reviewer were anonymised.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

doc/reviewer/briefing.md

@@ -1,12 +1,17 @@
 # Reviewer briefing — conformallab++
 
-> **Audience.** External reviewer with a discrete-conformal-geometry
-> background (Springborn / Bobenko alumnus, ~30 minutes lead-time
-> before the meeting).
+> **Audience.** Active researcher in discrete differential geometry —
+> specifically the research line around **decorated discrete conformal
+> equivalence**, **Penner coordinates on hyperbolic surfaces**,
+> **canonical Delaunay tessellations of decorated surfaces**, and
+> **hyperideal polyhedra**.  Treats the reader as a peer who is more
+> likely to *use* conformallab++ as numerical infrastructure for their
+> own future experiments than to merely evaluate it as a software
+> artefact.
 >
-> **Purpose of this document.** A single page they can read once
-> before the meeting and feel oriented — what the project is, what
-> we want from them, and where to look first.
+> **Purpose.** One page to read before the meeting: what is shipping,
+> which of the reader's research questions it could already support,
+> and where the gaps are that we would close together.
 
 ## In one paragraph