perf(transform-ast): one kitchen-sink suite per version pair (~95s → ~12s)

[pyramation]

Summary

@pgsql/transform-ast was the slowest CI job at ~95s, and essentially none of that was transform work. make-kitchen-sink.ts emitted one test file per (fixture file × version pair) — 278 × 5 = 1390 suites, each holding a single it() over ~17 statements. Every one of those suites paid the same fixed cost at module scope:

const fixtures = new FixtureTestUtils(13, 14);  // 6 WASM parsers + JSON.parse of a 2.8 MB generated.json

plus its own ts-jest compile and Jest module registry. Measured in isolation a single suite takes ~1.0s, of which the assertions are noise.

The generator now writes a shared manifest and five thin suites:

__tests__/kitchen-sink/
  fixtures.json      # { "misc-indexes": ["misc/indexes-1.sql", ...] }  — one copy, all pairs
  13-14.test.ts … 17-18.test.ts

const manifest = JSON.parse(readFileSync(join(__dirname, 'fixtures.json'), 'utf-8'));
const fixtures = new FixtureTestUtils(13, 14);
describe('13-14', () => {
  it.each(Object.entries(manifest))('%s', async (_name, tests) => fixtures.runFixtureTests(tests));
});

Same corpus, same assertions, same per-fixture test names in the report — 5 parser-set inits instead of 1390. npx jest in the package: 95s → 12s, 1443 passed.

Two related bits:

• The old shape silently tolerated dead suites: runFixtureTests([]) logs no filters provided, skipping tests and returns green. The generator now skips zero-statement fixtures outright, and the manifest covers all 23,491 statements (previously 23,477) — which surfaced misc/index-clause-ordering, added in fix(deparser): emit CREATE INDEX trailing clauses in grammar order #336 and never picked up by a transform-ast regeneration.
• NULLS NOT DISTINCT is PG15+, so those statements can't be parsed by the v13/v14 parsers; added the corresponding parserErrors skip entries, matching the existing MERGE / pg18-* precedent.

Link to Devin session: https://app.devin.ai/sessions/6e8bd0b058a944eeba4a3dbad12d8487
Requested by: @pyramation

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