Replace implemented column with CMMI maturity level

Drop the boolean implemented/not-implemented state in favor of a
mandatory CMMI maturity level enum (NONE, INITIAL, MANAGED, DEFINED,
QUANTITATIVELY_MANAGED, OPTIMIZING) stored as a Postgres enum type.

The migration backfills existing rows (NOT_IMPLEMENTED → NONE,
IMPLEMENTED → INITIAL), makes the column NOT NULL, and drops the old
implemented column and its enum type.

- maturityLevel is required on CreateControlInput and non-nullable (!)
  in the GraphQL schema
- CLI displays human-readable CMMI labels instead of raw enum tokens
- SOA table and published document use a single Maturity column in
  place of the old Implemented + Maturity columns
- Remove ControlImplementationState type and all implemented references
  across backend, frontend, CLI, MCP, n8n, and E2E tests

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/server/api/console/v1/control_resolvers.go

@@ -415,9 +415,8 @@ func (r *mutationResolver) CreateControl(ctx context.Context, input types.Create
 			Description:                 input.Description,
 			SectionTitle:                input.SectionTitle,
 			BestPractice:                input.BestPractice,
-			Implemented:                 input.Implemented,
-			NotImplementedJustification: input.NotImplementedJustification,
 			MaturityLevel:               input.MaturityLevel,
+			NotImplementedJustification: input.NotImplementedJustification,
 		},
 	)
 	if err != nil {
@@ -453,9 +452,8 @@ func (r *mutationResolver) UpdateControl(ctx context.Context, input types.Update
 			Description:                 gqlutils.UnwrapOmittable(input.Description),
 			SectionTitle:                input.SectionTitle,
 			BestPractice:                input.BestPractice,
-			Implemented:                 input.Implemented,
+			MaturityLevel:               input.MaturityLevel,
 			NotImplementedJustification: gqlutils.UnwrapOmittable(input.NotImplementedJustification),
-			MaturityLevel:               gqlutils.UnwrapOmittable(input.MaturityLevel),
 		},
 	)