Full postgres test suite on beta now fails: multiple test.skipIf(Date.now() < '2026-07-01') gates have expired

## Summary

Running the full `drizzle-kit` postgres test suite against unmodified `beta` today (2026-07-20) produces 8 failures, 740 passed (out of 749). Two are environmental (`POSTGIS_URL` not set in CI — unrelated to this issue). The other 6 all share the same root cause: they were written with a date-gated skip that has now expired, exposing tests for features/behavior that were never actually finished.

```js
test.skipIf(Date.now() < +new Date('2026-07-01'))('...', async () => { ... });
```

Since today is past 2026-07-01, these tests run for the first time in CI (rather than being silently skipped) and fail.

## Affected tests

| Test | File | Related issue | Notes |
|---|---|---|---|
| `alter integer type to text type with fk constraints` | `drizzle-kit/tests/postgres/pg-columns.test.ts` | #3589 | Comment: "After discussion it was decided to postpone this feature" |
| `alter enum values; enum value is column default; table with data` | `drizzle-kit/tests/postgres/pg-enums.test.ts` | #4982 | Tagged `// enhancement` |
| `add table #16` | `drizzle-kit/tests/postgres/pg-tables.test.ts` | #5603 | |
| `introspect sequences with table filter` | `drizzle-kit/tests/postgres/pull.test.ts` | #4144 | Comment: "this does not look like a bug... entity filter for sequences ??" |
| `introspect view #4` | `drizzle-kit/tests/postgres/pull.test.ts` | #4262 | Body contains a hardcoded `throw Error('')` placeholder |
| `introspect view #5` | `drizzle-kit/tests/postgres/pull.test.ts` | #4262 | Body contains a hardcoded `throw new Error()` placeholder |

## Impact

Every CI run against `beta` (and any PR branched from it) will now show these 6 as failing, with no code change required to trigger it — purely a function of wall-clock time. This can confuse contributors/reviewers into thinking a PR introduced regressions when it didn't (this came up while verifying #6043).

## Suggested resolution

For each of the 5 underlying issues (#3589, #4982, #5603, #4144, #4262), either:
1. Finish the design/implementation so the test can pass for real, or
2. Push the `skipIf` date further out if the feature is still genuinely undecided, or
3. Convert to `test.skip` (unconditional) with a tracking comment if there's no near-term plan, so the suite doesn't silently start failing again on some future date.

Happy to help verify once any of these land.

Run the full drizzle-kit PostgreSQL test suite and inspect the date-gated cases in pg-columns.test.ts, pg-enums.test.ts, pg-tables.test.ts, and pull.test.ts. Review related issues #3589, #4982, #5603, #4144, and #4262 to determine whether each test should pass or remain explicitly skipped; done means the six cases no longer fail unexpectedly in CI.

Written by the indexing model from the issue text.