Writes buffered facts into a SQLite file.

The whole dump is one transaction with journalling disabled. The database is a derived artefact rebuilt from scratch on every run, so there is nothing to protect against a crash halfway through: if the build dies you re-run it. That buys roughly an order of magnitude over the default durable settings on a few million rows.

Indexes are created after the load rather than before. Module and file names repeat constantly across facts, so both are memoised while folding; without that, inspect/1 on module atoms dominates the dump.