feat(io): conservative opt-in bend repair with tests and console CLI

Add OpenNest.IO/Bending/BendRepair: opt-in repair of unambiguous paired
ETCH/SCRIBE bend ticks, bounded to <=3.175 mm endpoint movement with
explicit source units. Cut geometry is never modified.

- CadImportOptions.BendRepair configures it; CadImportResult exposes
  per-bend BendRepairReports; CadImporter/Dxf wire it into import.
- Console: --repair-bends-mm <limit> --cad-units inches|mm prints
  per-bend reports for newly imported DXFs.
- New OpenNest.IO.Tests project (net8.0, synthetic DXFs, 30 tests)
  covering bend detection and repair, added to the solution.
- Update README.md and CLAUDE.md for the new pipeline and build/test
  instructions.

OpenNest.IO/CadImportResult.cs

@@ -24,6 +24,8 @@ namespace OpenNest.IO
         /// </summary>
         public List<Bend> Bends { get; set; } = new List<Bend>();
 
+        public List<Bending.BendRepairReport> BendRepairReports { get; set; } = new List<Bending.BendRepairReport>();
+
         /// <summary>
         /// Bounding box of <see cref="Entities"/> at import time. May be stale
         /// if callers mutate <see cref="Entities"/>; recompute if needed.