feat: add administrator repository (#11803)

Introduces the `administrators` relational table and repository layer
for the v3 backend, unifying instance, organization, project, and
project-grant membership into a single scoped model.

Closes #10220

## Changes

- **Domain**: `Administrator` struct, `AdministratorScope` enum,
`AdministratorRepository` interface with typed CRUD, column, condition,
and change helpers. Generated enumer and GoMock.
- **Migration** (`016`): `zitadel.administrators` table with a generated
`id`, scope-alignment check constraint, cascading foreign keys, and a
child `administrator_roles` table.
- **Repository**: CTE-based role mutations (`AddRole`, `RemoveRole`,
`SetRoles`) for atomicity. Roles aggregated via `ARRAY_AGG`.
- **Projection**: Event reducers for
`member.added/changed/removed/cascade_removed` across all four admin
scopes.
- **Fixes**: `Rows.Close()` error wrapping; `TextArray` nil-safe scan +
full `pgtype` array interface; `authorization` and `projectGrant` scan
helpers fixed for `ARRAY_AGG` under `database/sql`; removed unused `ctx`
parameter from `callReduce`.

---------

Co-authored-by: Marco Ardizzone <[email protected]>

backend/v3/storage/database/repository/authorization.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/zitadel/zitadel/backend/v3/domain"
 	"github.com/zitadel/zitadel/backend/v3/storage/database"
+	internaldb "github.com/zitadel/zitadel/internal/database"
 )
 
 var _ domain.AuthorizationRepository = (*authorization)(nil)
@@ -93,7 +94,7 @@ func (a authorization) Get(ctx context.Context, client database.QueryExecutor, o
 	if err != nil {
 		return nil, err
 	}
-	return getOne[domain.Authorization](ctx, client, builder)
+	return scanAuthorization(ctx, client, builder)
 }
 
 // List implements [domain.AuthorizationRepository].
@@ -106,7 +107,7 @@ func (a authorization) List(ctx context.Context, client database.QueryExecutor,
 	if err != nil {
 		return nil, err
 	}
-	return getMany[domain.Authorization](ctx, client, builder)
+	return scanAuthorizations(ctx, client, builder)
 }
 
 func (a authorization) prepareQuery(opts []database.QueryOption) (*database.StatementBuilder, error) {
@@ -196,6 +197,50 @@ func (a authorization) Delete(ctx context.Context, client database.QueryExecutor
 	return client.Exec(ctx, builder.String(), builder.Args()...)
 }
 
+// rawAuthorization is used for query collection because ARRAY_AGG roles cannot be
+// scanned directly into the domain model's []string field when the client is backed
+// by [database/sql]. The intermediate TextArray field works with both [database/sql] and pgx.
+type rawAuthorization struct {
+	domain.Authorization
+	Roles internaldb.TextArray[string] `db:"roles"`
+}
+
+func (a *rawAuthorization) toDomain() *domain.Authorization {
+	a.Authorization.Roles = []string(a.Roles)
+	return &a.Authorization
+}
+
+func scanAuthorization(ctx context.Context, client database.QueryExecutor, builder *database.StatementBuilder) (*domain.Authorization, error) {
+	rows, err := client.Query(ctx, builder.String(), builder.Args()...)
+	if err != nil {
+		return nil, err
+	}
+
+	var authorization rawAuthorization
+	if err = rows.(database.CollectableRows).CollectExactlyOneRow(&authorization); err != nil {
+		return nil, err
+	}
+	return authorization.toDomain(), nil
+}
+
+func scanAuthorizations(ctx context.Context, client database.QueryExecutor, builder *database.StatementBuilder) ([]*domain.Authorization, error) {
+	rows, err := client.Query(ctx, builder.String(), builder.Args()...)
+	if err != nil {
+		return nil, err
+	}
+
+	var authorizations []rawAuthorization
+	if err = rows.(database.CollectableRows).Collect(&authorizations); err != nil {
+		return nil, err
+	}
+
+	result := make([]*domain.Authorization, len(authorizations))
+	for i := range authorizations {
+		result[i] = authorizations[i].toDomain()
+	}
+	return result, nil
+}
+
 // -------------------------------------------------------------
 // columns
 // -------------------------------------------------------------