Result extras

These operators are available only on Result and help with error transformation, validation, and fallback chains.

Operator	Description	Usage
`mapErr`	Transform the error channel	`Err(e).mapErr(fn) → Err(newE)`
`mapBoth`	Transform both Ok and Err paths	`.mapBoth(okFn, errFn)`
`validate`	Run validators, accumulate all errors	`.validate([...validators])`
`Result.all`	All must succeed, returns tuple	`Result.all(r1, r2, ...) → Ok([...])`
`Result.any`	First Ok wins, or all errors	`Result.any(r1, r2, ...) → first Ok`
`tapErr`	Side effect for Err, returns self	`Err(e).tapErr(fn) → Err(e)`
`orElse`	Recover from error with fallback	`Err(e).orElse(fn) → fallback`
`flip`	Swap Ok and Err channels	`Ok(v).flip() → Err(v)`
`toOption`	Convert to Option (discards error)	`Ok(v).toOption() → Some(v)`

Operator	Description	Usage
`Result.fromNullable`	Err for null/undefined	`fromNullable(val, err)`
`Result.fromPredicate`	Create based on predicate	`fromPredicate(val, pred, err)`
`Result.tryCatch`	Catch sync exceptions	`tryCatch(fn, mapErr)`
`Result.tryAsyncCatch`	Catch async exceptions	`tryAsyncCatch(fn, mapErr).toPromise()`

validate supports sync and async validators; in async flows use await ...toPromise().
orElse is useful for fallback/recovery chains (try cache → try API → default).
tap/tapErr are for side effects (logging, metrics) without altering the pipeline.