Function engineSwap

engineSwap(options: EngineSwapOptions): Promise<EngineSwapResult>
Run an engine swap from code, no terminal needed.

Missing options are defaulted (see EngineSwapOptions) & the target side is created if it doesn't exist yet, so the minimum viable call is just a direction plus a reachable DATABASE_URL.
Parameters
- options: EngineSwapOptions
  Direction plus any overrides.
Returns Promise<EngineSwapResult>
A per table breakdown of what moved.
Throws
ConfigurationError if the direction is missing/invalid or no connection string can be resolved.

Remarks
A schema or table name that doesn't match ^[a-zA-Z0-9_-]+$ is skipped & reported in skippedNames, not thrown on => aborting halfway through would leave part of a shared database migrated and files already renamed. Nothing outside those names is read or written.

An interrupted run (SIGINT/SIGTERM) stops at the next boundary, leaves a journal in the data dir & sets aborted => run the same swap again to finish it. Nothing is deleted on the way out.
Example: Non interactive, overwrite whatever is in the target
```
await engineSwap({
  direction: 'up',
  onConflict: 'overwrite',
  onProgress: (line) => console.log(`[swap] ${line}`),
});
```
Example: Decide per table
```
await engineSwap({
  direction: 'up',
  onConflict: (c) => c.schema !== 'economy', // never clobber economy
});
```
- Defined in engine-swap.ts:1175