feat(CUB-28): [Extrudex] Define filament inventory database entities

Add storage_location and is_archived fields to Spool entity to complete
the filament inventory entity definition per CUB-28 requirements.

Changes:
- Spool entity: add IsArchived (bool, default false) and StorageLocation
  (nullable string, max 200) for physical inventory tracking
- SpoolConfiguration: add snake_case column mappings, defaults, and indexes
  (ix_spools_is_archived, ix_spools_active_archived composite)
- FilamentDtos: add IsArchived + StorageLocation to Response, Create, Update
- FilamentQueryDtos: add IncludeArchived and StorageLocation query filters
- FilamentsController: wire new fields into query, create, update, mapping
- FilamentValidators: add StorageLocation max-length validation

Build: PASS (0 errors)

backend/API/DTOs/Filaments/FilamentQueryDtos.cs

@@ -30,4 +30,11 @@ public class FilamentQueryParameters
 
     /// <summary>Optional filter by active status. True = active only, False = inactive only.</summary>
     public bool? IsActive { get; set; }
+
+    /// <summary>Whether to include archived spools in results. Defaults to false (excludes archived).
+    /// </summary>
+    public bool? IncludeArchived { get; set; }
+
+    /// <summary>Optional filter by storage location (case-insensitive partial match).</summary>
+    public string? StorageLocation { get; set; }
 }