Refactor MeasuresPage to use Relay fragments

Replace the client-side grouped-by-category view (fetching 500 items)
with a flat table using server-side filtering and cursor-based
pagination. Colocate GraphQL queries, fragments, and mutations in the
component file per console CLAUDE.md conventions.

Backend changes add a category filter to the measure list endpoints
(GraphQL, MCP) and a new measureCategories field on Organization.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/probo/framework_service.go

@@ -208,7 +208,7 @@ func (s FrameworkService) Export(
 							Direction: page.OrderDirectionAsc,
 						},
 					),
-					coredata.NewMeasureFilter(nil, nil),
+					coredata.NewMeasureFilter(nil, nil, nil),
 				)
 				if err != nil {
 					return fmt.Errorf("cannot load measures: %w", err)