sql-839: Report SQL string 'NULL' for table column defaults in mz_columns again - #40316

Undo the string "NULL" default from #40316 now that
terraform-provider-materialize v0.11.13 reads a SQL NULL column default
as no default
([DEX-197](https://linear.app/materializeinc/issue/DEX-197)). Table
columns again match every other relation in `mz_columns.default`, and
the PostgreSQL-compatible views go back to plain `IS NOT NULL` checks.
`information_schema.columns`, `pg_attribute`, and `pg_attrdef` report
the same results as before.

`materialize_table` is the only provider resource that reads
`mz_columns.default`.

### Release notes

This release will report SQL `NULL` instead of the string `'NULL'` in
`mz_catalog.mz_columns.default` for table columns without a default,
matching sources, views, and materialized views. If you manage tables
with the Materialize Terraform provider, upgrade the provider to
v0.11.13 or later before you upgrade Materialize.

Co-authored-by: Claude Opus 5.5 <[email protected]>

Generated with the fixed `yarn gen:types`. Adds mz_builtin_columns and
mz_builtin_index_columns. Builtin columns lose their Generated<>
wrappers, since MaterializeInc#40316 reports no default for them in pg_attribute.
Keeps the two hand-added TODO markers for mz >= 26.34.

### Motivation

`yarn gen:types` fails with `function "pg_get_serial_sequence" does not
exist`. kysely-codegen runs kysely's Postgres introspector for its table
query. Since the bump to kysely 0.28 (#35669), that query calls
`pg_get_serial_sequence`, which Materialize lacks. kysely 0.29 still
does. The query also lists only relkinds `r`, `v` and `p`, so the
catalog's builtin materialized views (`m`) never reached the types under
kysely-codegen 0.17. #40044's types were generated with both patched by
hand in `node_modules`.

This also bumps kysely to 0.29 and kysely-codegen to 0.20, superseding
#39686.

### Description

- `bin/kysely-codegen.ts` runs kysely-codegen programmatically with an
introspector that overrides only the table query. kysely-codegen's
materialized view query, enum handling and serializer still apply.
- The script writes the copyright header to `types/materialize.d.ts`.
The codegen output lacks it, and the copyright lint fails without it.
- `bin/generate-types` exits on errors, pulls the requested image (a
cached `latest` went stale), and stops the container on exit. Before,
each run left a container bound to port 6875, and the next run generated
types from that old container.
- kysely 0.28.17 → 0.29.8 and kysely-codegen 0.17 → 0.20.0:
- 0.29 rejects `limit(sql.raw(...))`. `rawLimit` and the lag history
limit now call `query.limit(sql.lit(n))`, which still inlines the limit
as a literal, as Materialize requires.
- `rawLimit` used to append its limit with `modifyEnd`. In 0.29,
compiling end modifiers calls `Array.prototype.toSorted`, which Chrome
109 lacks. No console query uses end modifiers now. Neither `rawLimit`
caller has an OFFSET or another end modifier, so the compiled SQL is
unchanged.
- kysely 0.29 is ESM-only and kysely-codegen 0.20 `require`s it, so
`yarn gen:types` needs Node 22.12 or later. CI and the Volta pin run
Node 26, and #39683 updates `engines.node`.
- `types/materialize.d.ts` is regenerated against v26.49.1.
kysely-codegen 0.17 and 0.20 produce identical output.
  - Adds `mz_builtin_columns` and `mz_builtin_index_columns`.
- Builtin columns lose their `Generated<>` wrappers, because #40316
changed `pg_attribute.atthasdef` to report no default for them. The
console only selects from these relations, where `Generated<T>` and `T`
read the same.
- Drops the two hand-added `TODO` markers from #39992. The generator now
emits `mz_cluster_auto_scaling_strategies` and
`mz_cluster_reconfigurations`, and `AUTO_SCALING_MIN_VERSION` still
gates them at runtime. The file is now exactly the generator output.

Worth checking on the preview, since these run the changed limits:
- the Query History list;
- a sink's Errors tab;
- the freshness lag charts on the environment overview and the cluster
pages.

🤖 Generated with [Claude Code](https://claude.com/claude-code)