[BUG]: node-postgres: db.execute() bypasses configured PostgreSQL type parsers for TIMESTAMPTZ

### Report hasn't been filed before.

- [x] I have verified that the bug I'm about to report hasn't been filed before.

### What version of `drizzle-orm` are you using?

0.45.2

### What version of `drizzle-kit` are you using?

0.31.10

### Other packages

_No response_

### Describe the Bug

## Summary

With Drizzle ORM `0.45.2` using the `node-postgres` driver, `db.execute()` overrides the PostgreSQL driver's configured type parser for `TIMESTAMPTZ` (OID `1184`) and returns the value as a string.

This produces inconsistent runtime types between:

- native `node-postgres` queries → `Date`
- Drizzle ORM typed queries → `Date`
- Drizzle `db.execute()` → `string`

## Environment

- Drizzle ORM: `0.45.2`
- Driver: `node-postgres` (`pg`)
- Database: PostgreSQL
- Column type: `timestamptz`
- Drizzle column mode: `date`

Schema:

```ts
export const ts = () =>
timestamp({
withTimezone: true,
precision: 3,
mode: 'date',
});

Start by reproducing the mismatch through Drizzle's db.execute() with the node-postgres driver, PostgreSQL TIMESTAMPTZ, and a configured OID 1184 parser. Compare the result with native node-postgres and Drizzle typed queries; done means db.execute() honors the configured parser and returns the consistent runtime type.

Written by the indexing model from the issue text.