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]>

internal/query/projection/event_testing_relational_test.go

@@ -85,7 +85,7 @@ func getTransactions(t *testing.T) (rawTx *sql.Tx, v3SQLTx *v3_sql.Transaction)
 //  4. the reducer function for the input event executes without errors
 //
 // Returns false if any of the above checks fails
-func callReduce(t *testing.T, ctx context.Context, tx *sql.Tx, projection handler.Projection, event eventstore.Event) bool {
+func callReduce(t *testing.T, tx *sql.Tx, projection handler.Projection, event eventstore.Event) bool {
 	reducers := projection.Reducers()
 	aggregateReducerIdx := slices.IndexFunc(reducers, func(r handler.AggregateReducer) bool {
 		return r.Aggregate == event.Aggregate().Type
@@ -111,6 +111,6 @@ func callReduce(t *testing.T, ctx context.Context, tx *sql.Tx, projection handle
 		return false
 	}
 
-	err = stmt.Execute(ctx, tx, "")
+	err = stmt.Execute(t.Context(), tx, "")
 	return assert.NoError(t, err)
 }