refactor(Archive): Clayworth surface via triangle group Δ(2,3,12)

Replace the 4048-line array-backed ClayworthSurface with an algebraic
construction from the triangle group Δ(2,3,12). The face rotation R
(order 12) and vertex rotation S (order 3) generate G₂(2) in its regular
representation on 12096 darts. Vertices, edges, and faces arise as
left cosets of ⟨S⟩, ⟨T⟩, ⟨R⟩ respectively.

The general TriangleGroupSurface construction derives a CellularSurface
from any finite quotient of Δ(2,3,r), with face_closed following from
the identity T = RS (the "other end" of a dart has the same vertex as
its R-successor, because S preserves vertex cosets).

Build time drops from >30 minutes (CI timeout) to ~50 seconds.

Author: RaggedR

Archive.lean

@@ -72,6 +72,7 @@ import Archive.MiuLanguage.DecisionNec
 import Archive.MiuLanguage.DecisionSuf
 import Archive.OxfordInvariants.Summer2021.Week3P1
 import Archive.Sensitivity
+import Archive.TriangleGroupSurface
 import Archive.VoltageGraphs
 import Archive.Wiedijk100Theorems.AbelRuffini
 import Archive.Wiedijk100Theorems.AreaOfACircle