feat(posts): add Cincinnati CI Fiber (TF5200) post-processor

New post-processor plugin OpenNest.Posts.CincinnatiCIFiber for the CI
Fiber laser family (nLight CLX / Beckhoff TF5200 / Precitec ProCutter,
e.g. the CI Fiber 4020 8kW). Named by machine family, not table size.

Emits the machine program contract of the Cincinnati-supplied sample NC
(12992-4SS_NEST.nc): V.E.* header, restart jump, per-part V.E.R4 blocks,
per-contour N labels with V.E.R3, skippable /L macro lines (L0/L2+G41
interior, L4+G42 exterior, L6 cut-on, ZHSOFF cut-end), G162 incremental
arc I/J, trimmed 3-decimal spaceless coordinates, CRLF, M50/M30/%.

Contour classification (interior vs exterior) derives from the material
side of the closed cut path, not hardcoded winding. SubProgramCall holes
are flattened to sheet coordinates (rotation-safe). Arc lead-ins are
rejected per TF5200 13.2.4.1 (first motion block after G41/G42 selection
must be linear). Table envelope (default 160.25 x 81.25 in) validated.

Tests: structure golden on a square-with-hole nest, rotated-hole flatten,
coordinate format, arc-lead-in rejection, table validation, suppressed/
scribe skipping, plus a SkippableFact regression against the real sample
NC (109 parts, 2071 contours, L2=1962, L4=109, perimeter vertices match
within 0.001). Fixtures configure through OpenNest.Tests/test-config.json
and the regression skips when absent.

OpenNest.Tests/OpenNest.Tests.csproj

@@ -29,6 +29,7 @@
     <ProjectReference Include="..\OpenNest.Engine\OpenNest.Engine.csproj" />
     <ProjectReference Include="..\OpenNest.IO\OpenNest.IO.csproj" />
     <ProjectReference Include="..\Posts\OpenNest.Posts.Cincinnati\OpenNest.Posts.Cincinnati.csproj" />
+    <ProjectReference Include="..\Posts\OpenNest.Posts.CincinnatiCIFiber\OpenNest.Posts.CincinnatiCIFiber.csproj" />
     <ProjectReference Include="..\Posts\OpenNest.Posts.GravographIS\OpenNest.Posts.GravographIS.csproj" />
   </ItemGroup>