Fix UNION with nested SELECT

[pratyushsinghal7]

Fixes #1264

Summary

Queries like SELECT * FROM (SELECT *, (SELECT COUNT(*) FROM ?) AS c FROM ? UNION CORRESPONDING SELECT * FROM ?) crashed with Cannot read property '0' of undefined, as did scalar subqueries nested inside another subquery's WHERE clause.

The parser hoists every parenthesized scalar subquery into a single statement-level queries list, and the compiled expressions reference this.queriesfn[queriesidx - 1] on their own query object — but only the outermost query ever received the compiled list, so any subquery reference evaluated inside a FROM subselect or inside another subquery found this.queriesfn undefined.

• share the compiled statement-level queriesfn list with nested compiled queries in compileQueries and with FROM subselects, so queriesidx references resolve at any nesting depth
• treat a FROM subselect's column list as unknown when it was compiled with dirtyColumns (e.g. SELECT * over parameter data), so the outer SELECT * expands from the data instead of projecting only the statically known columns
• add regression coverage for the queries from the issue

Testing

• bun test --preload ./test/bun-setup.js ./test/test1264.js (6 passed)
• bun run test-only (2194 passed, 213 skipped, 0 failed)
• bun x prettier --check src/40select.js src/420from.js test/test1264.js