feat(server): add a company material list with list/add endpoints

Nests, drawings and releases store material and grade as free text, so
there was no canonical list for clients to suggest from or to fix
spelling against. Schema v10 adds materials and material_grades keyed by
SharedListNames.Key, with GET/POST /api/materials. Adding is idempotent
by key and keeps the first spelling.

The tables start empty: the materials already stored did not import
cleanly, so the list is filled through the API instead. Existing
free-text columns are unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest.Server/Program.cs

@@ -142,6 +142,7 @@ app.MapPost("/api/nests/{id:guid}/revisions/{revision:int}/restore", (Guid id, i
 app.MapDrawingLibrary();
 app.MapDrawingSets();
 app.MapReleases();
+app.MapMaterials();
 
 app.Run();