fix: support Drizzle folder migrations

[HuakunShen]

Summary

• Fix migrate() so Drizzle v1/RC Folder V3 paths like .../20260605110000_add_users/migration.sql use a stable parent-folder migration id instead of the repeated migration.sql basename.
• Keep existing flat migration filenames backward compatible and add legacy recovery for databases that already recorded the old migration.sql marker.
• Add Bun TypeScript regression tests, test typechecking, README migration docs, and bump the npm package to 0.1.1-beta.0 for beta publishing.

Root Cause

Drizzle Folder V3 stores each migration SQL payload as migration.sql inside a uniquely named migration folder. The previous parser recorded only the SQL file basename in __drizzle_migrations.hash, so multiple migrations collided on migration.sql and could trigger UNIQUE constraint failed: __drizzle_migrations.hash.

Validation

• ./node_modules/.bin/tsc --noEmit
• ./node_modules/.bin/tsc --noEmit -p test/tsconfig.json
• pnpm test
• npm pack --dry-run --registry=https://registry.npmjs.org/