UPDATE incorrectly permits a windowed target-table subquery

## What happened

Dolt exhibits this behavior: UPDATE incorrectly permits a target-table subquery containing a window expression.

## Environment

Dolt main commit `59fb843bf6a4b653d7c8b6d997a603b10cf279d9` (`dolt version 2.2.3`).

## How to reproduce

```sql
CREATE TABLE t(i INT PRIMARY KEY, j INT, k INT);
INSERT INTO t VALUES (1,2,3),(2,3,4);
UPDATE t
SET k = 30
WHERE i IN (SELECT FIRST_VALUE(i) OVER () FROM t WHERE j = 2);
SELECT i,j,k FROM t ORDER BY i;
```

## Expected result

MySQL 8.0.43 fresh run:

```text
ERROR 1093 (HY000) at line 3: You can't specify target table 't' for update in FROM clause
```

MySQL rejects this statement with `ERROR 1093 (HY000): You can't specify target table 't' for update in FROM clause`; the target table is read directly by the windowed subquery.

## Actual result

Dolt executes the update and returns:

```text
i j k
1 2 30
2 3 4
```

Start by running the SQL reproduction in the issue and comparing Dolt's result with MySQL 8.0.43. Trace the UPDATE and windowed-subquery validation entry points, then add a regression test showing that a target-table windowed subquery is rejected with the expected error behavior.

Written by the indexing model from the issue text.