[Compatibility]: unsigned subtraction ignores NO_UNSIGNED_SUBTRACTION mode

## Summary

MatrixOne ignores the `NO_UNSIGNED_SUBTRACTION` SQL-mode distinction for unsigned integer subtraction. `CAST(0 AS UNSIGNED) - 1` returns `-1` in every tested mode, whereas MySQL returns an out-of-range error by default and only returns `-1` when `NO_UNSIGNED_SUBTRACTION` is explicitly enabled.

## Environment

- MatrixOne official `main`: `99ed717b769e261b842c2f17345bd65865fc1470`
- Clean local single-CN build and isolated data directory
- Reproduced identically in 3/3 runs

## Reproduction

```sql
SET SESSION sql_mode = '';
SELECT @@sql_mode, CAST(0 AS UNSIGNED) - 1;
-- '' | -1

SET SESSION sql_mode = 'STRICT_TRANS_TABLES';
SELECT @@sql_mode, CAST(0 AS UNSIGNED) - 1;
-- STRICT_TRANS_TABLES | -1

SET SESSION sql_mode = 'NO_UNSIGNED_SUBTRACTION';
SELECT @@sql_mode, CAST(0 AS UNSIGNED) - 1;
-- NO_UNSIGNED_SUBTRACTION | -1
```

## Expected behavior

MySQL's documented default is unsigned subtraction when either integer operand is unsigned. Therefore `CAST(0 AS UNSIGNED) - 1` must raise an unsigned `BIGINT` out-of-range error unless `NO_UNSIGNED_SUBTRACTION` is enabled; only with that mode should the signed result `-1` be returned.

## Scope control

Assigning the result back to a `BIGINT UNSIGNED` column raises an out-of-range error and leaves the row unchanged in both tested modes. The discrepancy is specifically expression evaluation/type selection: the read expression already behaves as if `NO_UNSIGNED_SUBTRACTION` were always on, while the session mode value does not change it.

## Suggested regression coverage

Test unsigned subtraction in empty mode, strict mode, and `NO_UNSIGNED_SUBTRACTION`, both as a scalar expression and in an update to an unsigned column. Assert the distinct MySQL results and SQLSTATEs.